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xen: remove tmem driver

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The Xen tmem (transcendent memory) driver can be removed, as the
related Xen hypervisor feature never made it past the "experimental"
state and will be removed in future Xen versions (>= 4.13).

The xen-selfballoon driver depends on tmem, so it can be removed, too.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2019-07-14 14:04:14 +02:00
parent 090d54bcbc
commit 814bbf49dc
8 changed files with 0 additions and 1074 deletions
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21
Documentation/admin-guide/kernel-parameters.txt
View File

@ -4674,27 +4674,6 @@
Force threading of all interrupt handlers except those
marked explicitly IRQF_NO_THREAD.
tmem [KNL,XEN]
Enable the Transcendent memory driver if built-in.
tmem.cleancache=0|1 [KNL, XEN]
Default is on (1). Disable the usage of the cleancache
API to send anonymous pages to the hypervisor.
tmem.frontswap=0|1 [KNL, XEN]
Default is on (1). Disable the usage of the frontswap
API to send swap pages to the hypervisor. If disabled
the selfballooning and selfshrinking are force disabled.
tmem.selfballooning=0|1 [KNL, XEN]
Default is on (1). Disable the driving of swap pages
to the hypervisor.
tmem.selfshrinking=0|1 [KNL, XEN]
Default is on (1). Partial swapoff that immediately
transfers pages from Xen hypervisor back to the
kernel based on different criteria.
topology= [S390]
Format: {off | on}
Specify if the kernel should make use of the cpu

23
drivers/xen/Kconfig
View File

@ -10,21 +10,6 @@ config XEN_BALLOON
the system to expand the domain's memory allocation, or alternatively
return unneeded memory to the system.
config XEN_SELFBALLOONING
bool "Dynamically self-balloon kernel memory to target"
depends on XEN && XEN_BALLOON && CLEANCACHE && SWAP && XEN_TMEM
help
Self-ballooning dynamically balloons available kernel memory driven
by the current usage of anonymous memory ("committed AS") and
controlled by various sysfs-settable parameters. Configuring
FRONTSWAP is highly recommended; if it is not configured, self-
ballooning is disabled by default. If FRONTSWAP is configured,
frontswap-selfshrinking is enabled by default but can be disabled
with the 'tmem.selfshrink=0' kernel boot parameter; and self-ballooning
is enabled by default but can be disabled with the 'tmem.selfballooning=0'
kernel boot parameter. Note that systems without a sufficiently
large swap device should not enable self-ballooning.
config XEN_BALLOON_MEMORY_HOTPLUG
bool "Memory hotplug support for Xen balloon driver"
depends on XEN_BALLOON && MEMORY_HOTPLUG
@ -191,14 +176,6 @@ config SWIOTLB_XEN
def_bool y
select SWIOTLB
config XEN_TMEM
tristate
depends on !ARM && !ARM64
default m if (CLEANCACHE || FRONTSWAP)
help
Shim to interface in-kernel Transcendent Memory hooks
(e.g. cleancache and frontswap) to Xen tmem hypercalls.
config XEN_PCIDEV_BACKEND
tristate "Xen PCI-device backend driver"
depends on PCI && X86 && XEN

2
drivers/xen/Makefile
View File

@ -17,14 +17,12 @@ dom0-$(CONFIG_X86) += pcpu.o
obj-$(CONFIG_XEN_DOM0) += $(dom0-y)
obj-$(CONFIG_BLOCK) += biomerge.o
obj-$(CONFIG_XEN_BALLOON) += xen-balloon.o
obj-$(CONFIG_XEN_SELFBALLOONING) += xen-selfballoon.o
obj-$(CONFIG_XEN_DEV_EVTCHN) += xen-evtchn.o
obj-$(CONFIG_XEN_GNTDEV) += xen-gntdev.o
obj-$(CONFIG_XEN_GRANT_DEV_ALLOC) += xen-gntalloc.o
obj-$(CONFIG_XENFS) += xenfs/
obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
obj-$(CONFIG_XEN_PVHVM) += platform-pci.o
obj-$(CONFIG_XEN_TMEM) += tmem.o
obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o
obj-$(CONFIG_XEN_MCE_LOG) += mcelog.o
obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/

419
drivers/xen/tmem.c
View File

@ -1,419 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Xen implementation for transcendent memory (tmem)
*
* Copyright (C) 2009-2011 Oracle Corp. All rights reserved.
* Author: Dan Magenheimer
*/
#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/cleancache.h>
#include <linux/frontswap.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/page.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
#include <xen/tmem.h>
#ifndef CONFIG_XEN_TMEM_MODULE
bool __read_mostly tmem_enabled = false;
static int __init enable_tmem(char *s)
{
tmem_enabled = true;
return 1;
}
__setup("tmem", enable_tmem);
#endif
#ifdef CONFIG_CLEANCACHE
static bool cleancache __read_mostly = true;
module_param(cleancache, bool, S_IRUGO);
static bool selfballooning __read_mostly = true;
module_param(selfballooning, bool, S_IRUGO);
#endif /* CONFIG_CLEANCACHE */
#ifdef CONFIG_FRONTSWAP
static bool frontswap __read_mostly = true;
module_param(frontswap, bool, S_IRUGO);
#else /* CONFIG_FRONTSWAP */
#define frontswap (0)
#endif /* CONFIG_FRONTSWAP */
#ifdef CONFIG_XEN_SELFBALLOONING
static bool selfshrinking __read_mostly = true;
module_param(selfshrinking, bool, S_IRUGO);
#endif /* CONFIG_XEN_SELFBALLOONING */
#define TMEM_CONTROL 0
#define TMEM_NEW_POOL 1
#define TMEM_DESTROY_POOL 2
#define TMEM_NEW_PAGE 3
#define TMEM_PUT_PAGE 4
#define TMEM_GET_PAGE 5
#define TMEM_FLUSH_PAGE 6
#define TMEM_FLUSH_OBJECT 7
#define TMEM_READ 8
#define TMEM_WRITE 9
#define TMEM_XCHG 10
/* Bits for HYPERVISOR_tmem_op(TMEM_NEW_POOL) */
#define TMEM_POOL_PERSIST 1
#define TMEM_POOL_SHARED 2
#define TMEM_POOL_PAGESIZE_SHIFT 4
#define TMEM_VERSION_SHIFT 24
struct tmem_pool_uuid {
u64 uuid_lo;
u64 uuid_hi;
};
struct tmem_oid {
u64 oid[3];
};
#define TMEM_POOL_PRIVATE_UUID { 0, 0 }
/* flags for tmem_ops.new_pool */
#define TMEM_POOL_PERSIST 1
#define TMEM_POOL_SHARED 2
/* xen tmem foundation ops/hypercalls */
static inline int xen_tmem_op(u32 tmem_cmd, u32 tmem_pool, struct tmem_oid oid,
u32 index, unsigned long gmfn, u32 tmem_offset, u32 pfn_offset, u32 len)
{
struct tmem_op op;
int rc = 0;
op.cmd = tmem_cmd;
op.pool_id = tmem_pool;
op.u.gen.oid[0] = oid.oid[0];
op.u.gen.oid[1] = oid.oid[1];
op.u.gen.oid[2] = oid.oid[2];
op.u.gen.index = index;
op.u.gen.tmem_offset = tmem_offset;
op.u.gen.pfn_offset = pfn_offset;
op.u.gen.len = len;
set_xen_guest_handle(op.u.gen.gmfn, (void *)gmfn);
rc = HYPERVISOR_tmem_op(&op);
return rc;
}
static int xen_tmem_new_pool(struct tmem_pool_uuid uuid,
u32 flags, unsigned long pagesize)
{
struct tmem_op op;
int rc = 0, pageshift;
for (pageshift = 0; pagesize != 1; pageshift++)
pagesize >>= 1;
flags |= (pageshift - 12) << TMEM_POOL_PAGESIZE_SHIFT;
flags |= TMEM_SPEC_VERSION << TMEM_VERSION_SHIFT;
op.cmd = TMEM_NEW_POOL;
op.u.new.uuid[0] = uuid.uuid_lo;
op.u.new.uuid[1] = uuid.uuid_hi;
op.u.new.flags = flags;
rc = HYPERVISOR_tmem_op(&op);
return rc;
}
/* xen generic tmem ops */
static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
u32 index, struct page *page)
{
return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
xen_page_to_gfn(page), 0, 0, 0);
}
static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
u32 index, struct page *page)
{
return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
xen_page_to_gfn(page), 0, 0, 0);
}
static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index)
{
return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, oid, index,
0, 0, 0, 0);
}
static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid)
{
return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
}
#ifdef CONFIG_CLEANCACHE
static int xen_tmem_destroy_pool(u32 pool_id)
{
struct tmem_oid oid = { { 0 } };
return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
}
/* cleancache ops */
static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
pgoff_t index, struct page *page)
{
u32 ind = (u32) index;
struct tmem_oid oid = *(struct tmem_oid *)&key;
if (pool < 0)
return;
if (ind != index)
return;
mb(); /* ensure page is quiescent; tmem may address it with an alias */
(void)xen_tmem_put_page((u32)pool, oid, ind, page);
}
static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key,
pgoff_t index, struct page *page)
{
u32 ind = (u32) index;
struct tmem_oid oid = *(struct tmem_oid *)&key;
int ret;
/* translate return values to linux semantics */
if (pool < 0)
return -1;
if (ind != index)
return -1;
ret = xen_tmem_get_page((u32)pool, oid, ind, page);
if (ret == 1)
return 0;
else
return -1;
}
static void tmem_cleancache_flush_page(int pool, struct cleancache_filekey key,
pgoff_t index)
{
u32 ind = (u32) index;
struct tmem_oid oid = *(struct tmem_oid *)&key;
if (pool < 0)
return;
if (ind != index)
return;
(void)xen_tmem_flush_page((u32)pool, oid, ind);
}
static void tmem_cleancache_flush_inode(int pool, struct cleancache_filekey key)
{
struct tmem_oid oid = *(struct tmem_oid *)&key;
if (pool < 0)
return;
(void)xen_tmem_flush_object((u32)pool, oid);
}
static void tmem_cleancache_flush_fs(int pool)
{
if (pool < 0)
return;
(void)xen_tmem_destroy_pool((u32)pool);
}
static int tmem_cleancache_init_fs(size_t pagesize)
{
struct tmem_pool_uuid uuid_private = TMEM_POOL_PRIVATE_UUID;
return xen_tmem_new_pool(uuid_private, 0, pagesize);
}
static int tmem_cleancache_init_shared_fs(uuid_t *uuid, size_t pagesize)
{
struct tmem_pool_uuid shared_uuid;
shared_uuid.uuid_lo = *(u64 *)&uuid->b[0];
shared_uuid.uuid_hi = *(u64 *)&uuid->b[8];
return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
}
static const struct cleancache_ops tmem_cleancache_ops = {
.put_page = tmem_cleancache_put_page,
.get_page = tmem_cleancache_get_page,
.invalidate_page = tmem_cleancache_flush_page,
.invalidate_inode = tmem_cleancache_flush_inode,
.invalidate_fs = tmem_cleancache_flush_fs,
.init_shared_fs = tmem_cleancache_init_shared_fs,
.init_fs = tmem_cleancache_init_fs
};
#endif
#ifdef CONFIG_FRONTSWAP
/* frontswap tmem operations */
/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
static int tmem_frontswap_poolid;
/*
* Swizzling increases objects per swaptype, increasing tmem concurrency
* for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS
*/
#define SWIZ_BITS 4
#define SWIZ_MASK ((1 << SWIZ_BITS) - 1)
#define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
#define iswiz(_ind) (_ind >> SWIZ_BITS)
static inline struct tmem_oid oswiz(unsigned type, u32 ind)
{
struct tmem_oid oid = { .oid = { 0 } };
oid.oid[0] = _oswiz(type, ind);
return oid;
}
/* returns 0 if the page was successfully put into frontswap, -1 if not */
static int tmem_frontswap_store(unsigned type, pgoff_t offset,
struct page *page)
{
u64 ind64 = (u64)offset;
u32 ind = (u32)offset;
int pool = tmem_frontswap_poolid;
int ret;
/* THP isn't supported */
if (PageTransHuge(page))
return -1;
if (pool < 0)
return -1;
if (ind64 != ind)
return -1;
mb(); /* ensure page is quiescent; tmem may address it with an alias */
ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), page);
/* translate Xen tmem return values to linux semantics */
if (ret == 1)
return 0;
else
return -1;
}
/*
* returns 0 if the page was successfully gotten from frontswap, -1 if
* was not present (should never happen!)
*/
static int tmem_frontswap_load(unsigned type, pgoff_t offset,
struct page *page)
{
u64 ind64 = (u64)offset;
u32 ind = (u32)offset;
int pool = tmem_frontswap_poolid;
int ret;
if (pool < 0)
return -1;
if (ind64 != ind)
return -1;
ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), page);
/* translate Xen tmem return values to linux semantics */
if (ret == 1)
return 0;
else
return -1;
}
/* flush a single page from frontswap */
static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset)
{
u64 ind64 = (u64)offset;
u32 ind = (u32)offset;
int pool = tmem_frontswap_poolid;
if (pool < 0)
return;
if (ind64 != ind)
return;
(void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind));
}
/* flush all pages from the passed swaptype */
static void tmem_frontswap_flush_area(unsigned type)
{
int pool = tmem_frontswap_poolid;
int ind;
if (pool < 0)
return;
for (ind = SWIZ_MASK; ind >= 0; ind--)
(void)xen_tmem_flush_object(pool, oswiz(type, ind));
}
static void tmem_frontswap_init(unsigned ignored)
{
struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID;
/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
if (tmem_frontswap_poolid < 0)
tmem_frontswap_poolid =
xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);
}
static struct frontswap_ops tmem_frontswap_ops = {
.store = tmem_frontswap_store,
.load = tmem_frontswap_load,
.invalidate_page = tmem_frontswap_flush_page,
.invalidate_area = tmem_frontswap_flush_area,
.init = tmem_frontswap_init
};
#endif
static int __init xen_tmem_init(void)
{
if (!xen_domain())
return 0;
#ifdef CONFIG_FRONTSWAP
if (tmem_enabled && frontswap) {
char *s = "";
tmem_frontswap_poolid = -1;
frontswap_register_ops(&tmem_frontswap_ops);
pr_info("frontswap enabled, RAM provided by Xen Transcendent Memory%s\n",
s);
}
#endif
#ifdef CONFIG_CLEANCACHE
BUILD_BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
if (tmem_enabled && cleancache) {
int err;
err = cleancache_register_ops(&tmem_cleancache_ops);
if (err)
pr_warn("xen-tmem: failed to enable cleancache: %d\n",
err);
else
pr_info("cleancache enabled, RAM provided by "
"Xen Transcendent Memory\n");
}
#endif
#ifdef CONFIG_XEN_SELFBALLOONING
/*
* There is no point of driving pages to the swap system if they
* aren't going anywhere in tmem universe.
*/
if (!frontswap) {
selfshrinking = false;
selfballooning = false;
}
xen_selfballoon_init(selfballooning, selfshrinking);
#endif
return 0;
}
module_init(xen_tmem_init)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dan Magenheimer <dan.magenheimer@oracle.com>");
MODULE_DESCRIPTION("Shim to Xen transcendent memory");

2
drivers/xen/xen-balloon.c
View File

@ -129,8 +129,6 @@ void xen_balloon_init(void)
{
register_balloon(&balloon_dev);
register_xen_selfballooning(&balloon_dev);
register_xenstore_notifier(&xenstore_notifier);
}
EXPORT_SYMBOL_GPL(xen_balloon_init);

579
drivers/xen/xen-selfballoon.c
View File

@ -1,579 +0,0 @@
// SPDX-License-Identifier: GPL-2.0
/******************************************************************************
* Xen selfballoon driver (and optional frontswap self-shrinking driver)
*
* Copyright (c) 2009-2011, Dan Magenheimer, Oracle Corp.
*
* This code complements the cleancache and frontswap patchsets to optimize
* support for Xen Transcendent Memory ("tmem"). The policy it implements
* is rudimentary and will likely improve over time, but it does work well
* enough today.
*
* Two functionalities are implemented here which both use "control theory"
* (feedback) to optimize memory utilization. In a virtualized environment
* such as Xen, RAM is often a scarce resource and we would like to ensure
* that each of a possibly large number of virtual machines is using RAM
* efficiently, i.e. using as little as possible when under light load
* and obtaining as much as possible when memory demands are high.
* Since RAM needs vary highly dynamically and sometimes dramatically,
* "hysteresis" is used, that is, memory target is determined not just
* on current data but also on past data stored in the system.
*
* "Selfballooning" creates memory pressure by managing the Xen balloon
* driver to decrease and increase available kernel memory, driven
* largely by the target value of "Committed_AS" (see /proc/meminfo).
* Since Committed_AS does not account for clean mapped pages (i.e. pages
* in RAM that are identical to pages on disk), selfballooning has the
* affect of pushing less frequently used clean pagecache pages out of
* kernel RAM and, presumably using cleancache, into Xen tmem where
* Xen can more efficiently optimize RAM utilization for such pages.
*
* When kernel memory demand unexpectedly increases faster than Xen, via
* the selfballoon driver, is able to (or chooses to) provide usable RAM,
* the kernel may invoke swapping. In most cases, frontswap is able
* to absorb this swapping into Xen tmem. However, due to the fact
* that the kernel swap subsystem assumes swapping occurs to a disk,
* swapped pages may sit on the disk for a very long time; even if
* the kernel knows the page will never be used again. This is because
* the disk space costs very little and can be overwritten when
* necessary. When such stale pages are in frontswap, however, they
* are taking up valuable real estate. "Frontswap selfshrinking" works
* to resolve this: When frontswap activity is otherwise stable
* and the guest kernel is not under memory pressure, the "frontswap
* selfshrinking" accounts for this by providing pressure to remove some
* pages from frontswap and return them to kernel memory.
*
* For both "selfballooning" and "frontswap-selfshrinking", a worker
* thread is used and sysfs tunables are provided to adjust the frequency
* and rate of adjustments to achieve the goal, as well as to disable one
* or both functions independently.
*
* While some argue that this functionality can and should be implemented
* in userspace, it has been observed that bad things happen (e.g. OOMs).
*
* System configuration note: Selfballooning should not be enabled on
* systems without a sufficiently large swap device configured; for best
* results, it is recommended that total swap be increased by the size
* of the guest memory. Note, that selfballooning should be disabled by default
* if frontswap is not configured. Similarly selfballooning should be enabled
* by default if frontswap is configured and can be disabled with the
* "tmem.selfballooning=0" kernel boot option. Finally, when frontswap is
* configured, frontswap-selfshrinking can be disabled with the
* "tmem.selfshrink=0" kernel boot option.
*
* Selfballooning is disallowed in domain0 and force-disabled.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/swap.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/workqueue.h>
#include <linux/device.h>
#include <xen/balloon.h>
#include <xen/tmem.h>
#include <xen/xen.h>
/* Enable/disable with sysfs. */
static int xen_selfballooning_enabled __read_mostly;
/*
* Controls rate at which memory target (this iteration) approaches
* ultimate goal when memory need is increasing (up-hysteresis) or
* decreasing (down-hysteresis). Higher values of hysteresis cause
* slower increases/decreases. The default values for the various
* parameters were deemed reasonable by experimentation, may be
* workload-dependent, and can all be adjusted via sysfs.
*/
static unsigned int selfballoon_downhysteresis __read_mostly = 8;
static unsigned int selfballoon_uphysteresis __read_mostly = 1;
/* In HZ, controls frequency of worker invocation. */
static unsigned int selfballoon_interval __read_mostly = 5;
/*
* Minimum usable RAM in MB for selfballooning target for balloon.
* If non-zero, it is added to totalreserve_pages and self-ballooning
* will not balloon below the sum. If zero, a piecewise linear function
* is calculated as a minimum and added to totalreserve_pages. Note that
* setting this value indiscriminately may cause OOMs and crashes.
*/
static unsigned int selfballoon_min_usable_mb;
/*
* Amount of RAM in MB to add to the target number of pages.
* Can be used to reserve some more room for caches and the like.
*/
static unsigned int selfballoon_reserved_mb;
static void selfballoon_process(struct work_struct *work);
static DECLARE_DELAYED_WORK(selfballoon_worker, selfballoon_process);
#ifdef CONFIG_FRONTSWAP
#include <linux/frontswap.h>
/* Enable/disable with sysfs. */
static bool frontswap_selfshrinking __read_mostly;
/*
* The default values for the following parameters were deemed reasonable
* by experimentation, may be workload-dependent, and can all be
* adjusted via sysfs.
*/
/* Control rate for frontswap shrinking. Higher hysteresis is slower. */
static unsigned int frontswap_hysteresis __read_mostly = 20;
/*
* Number of selfballoon worker invocations to wait before observing that
* frontswap selfshrinking should commence. Note that selfshrinking does
* not use a separate worker thread.
*/
static unsigned int frontswap_inertia __read_mostly = 3;
/* Countdown to next invocation of frontswap_shrink() */
static unsigned long frontswap_inertia_counter;
/*
* Invoked by the selfballoon worker thread, uses current number of pages
* in frontswap (frontswap_curr_pages()), previous status, and control
* values (hysteresis and inertia) to determine if frontswap should be
* shrunk and what the new frontswap size should be. Note that
* frontswap_shrink is essentially a partial swapoff that immediately
* transfers pages from the "swap device" (frontswap) back into kernel
* RAM; despite the name, frontswap "shrinking" is very different from
* the "shrinker" interface used by the kernel MM subsystem to reclaim
* memory.
*/
static void frontswap_selfshrink(void)
{
static unsigned long cur_frontswap_pages;
unsigned long last_frontswap_pages;
unsigned long tgt_frontswap_pages;
last_frontswap_pages = cur_frontswap_pages;
cur_frontswap_pages = frontswap_curr_pages();
if (!cur_frontswap_pages ||
(cur_frontswap_pages > last_frontswap_pages)) {
frontswap_inertia_counter = frontswap_inertia;
return;
}
if (frontswap_inertia_counter && --frontswap_inertia_counter)
return;
if (cur_frontswap_pages <= frontswap_hysteresis)
tgt_frontswap_pages = 0;
else
tgt_frontswap_pages = cur_frontswap_pages -
(cur_frontswap_pages / frontswap_hysteresis);
frontswap_shrink(tgt_frontswap_pages);
frontswap_inertia_counter = frontswap_inertia;
}
#endif /* CONFIG_FRONTSWAP */
#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
#define PAGES2MB(pages) ((pages) >> (20 - PAGE_SHIFT))
/*
* Use current balloon size, the goal (vm_committed_as), and hysteresis
* parameters to set a new target balloon size
*/
static void selfballoon_process(struct work_struct *work)
{
unsigned long cur_pages, goal_pages, tgt_pages, floor_pages;
unsigned long useful_pages;
bool reset_timer = false;
if (xen_selfballooning_enabled) {
cur_pages = totalram_pages();
tgt_pages = cur_pages; /* default is no change */
goal_pages = vm_memory_committed() +
totalreserve_pages +
MB2PAGES(selfballoon_reserved_mb);
#ifdef CONFIG_FRONTSWAP
/* allow space for frontswap pages to be repatriated */
if (frontswap_selfshrinking)
goal_pages += frontswap_curr_pages();
#endif
if (cur_pages > goal_pages)
tgt_pages = cur_pages -
((cur_pages - goal_pages) /
selfballoon_downhysteresis);
else if (cur_pages < goal_pages)
tgt_pages = cur_pages +
((goal_pages - cur_pages) /
selfballoon_uphysteresis);
/* else if cur_pages == goal_pages, no change */
useful_pages = max_pfn - totalreserve_pages;
if (selfballoon_min_usable_mb != 0)
floor_pages = totalreserve_pages +
MB2PAGES(selfballoon_min_usable_mb);
/* piecewise linear function ending in ~3% slope */
else if (useful_pages < MB2PAGES(16))
floor_pages = max_pfn; /* not worth ballooning */
else if (useful_pages < MB2PAGES(64))
floor_pages = totalreserve_pages + MB2PAGES(16) +
((useful_pages - MB2PAGES(16)) >> 1);
else if (useful_pages < MB2PAGES(512))
floor_pages = totalreserve_pages + MB2PAGES(40) +
((useful_pages - MB2PAGES(40)) >> 3);
else /* useful_pages >= MB2PAGES(512) */
floor_pages = totalreserve_pages + MB2PAGES(99) +
((useful_pages - MB2PAGES(99)) >> 5);
if (tgt_pages < floor_pages)
tgt_pages = floor_pages;
balloon_set_new_target(tgt_pages +
balloon_stats.current_pages - totalram_pages());
reset_timer = true;
}
#ifdef CONFIG_FRONTSWAP
if (frontswap_selfshrinking) {
frontswap_selfshrink();
reset_timer = true;
}
#endif
if (reset_timer)
schedule_delayed_work(&selfballoon_worker,
selfballoon_interval * HZ);
}
#ifdef CONFIG_SYSFS
#include <linux/capability.h>
#define SELFBALLOON_SHOW(name, format, args...) \
static ssize_t show_##name(struct device *dev, \
struct device_attribute *attr, \
char *buf) \
{ \
return sprintf(buf, format, ##args); \
}
SELFBALLOON_SHOW(selfballooning, "%d\n", xen_selfballooning_enabled);
static ssize_t store_selfballooning(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
bool was_enabled = xen_selfballooning_enabled;
unsigned long tmp;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &tmp);
if (err)
return err;
if ((tmp != 0) && (tmp != 1))
return -EINVAL;
xen_selfballooning_enabled = !!tmp;
if (!was_enabled && xen_selfballooning_enabled)
schedule_delayed_work(&selfballoon_worker,
selfballoon_interval * HZ);
return count;
}
static DEVICE_ATTR(selfballooning, S_IRUGO | S_IWUSR,
show_selfballooning, store_selfballooning);
SELFBALLOON_SHOW(selfballoon_interval, "%d\n", selfballoon_interval);
static ssize_t store_selfballoon_interval(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err)
return err;
if (val == 0)
return -EINVAL;
selfballoon_interval = val;
return count;
}
static DEVICE_ATTR(selfballoon_interval, S_IRUGO | S_IWUSR,
show_selfballoon_interval, store_selfballoon_interval);
SELFBALLOON_SHOW(selfballoon_downhys, "%d\n", selfballoon_downhysteresis);
static ssize_t store_selfballoon_downhys(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err)
return err;
if (val == 0)
return -EINVAL;
selfballoon_downhysteresis = val;
return count;
}
static DEVICE_ATTR(selfballoon_downhysteresis, S_IRUGO | S_IWUSR,
show_selfballoon_downhys, store_selfballoon_downhys);
SELFBALLOON_SHOW(selfballoon_uphys, "%d\n", selfballoon_uphysteresis);
static ssize_t store_selfballoon_uphys(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err)
return err;
if (val == 0)
return -EINVAL;
selfballoon_uphysteresis = val;
return count;
}
static DEVICE_ATTR(selfballoon_uphysteresis, S_IRUGO | S_IWUSR,
show_selfballoon_uphys, store_selfballoon_uphys);
SELFBALLOON_SHOW(selfballoon_min_usable_mb, "%d\n",
selfballoon_min_usable_mb);
static ssize_t store_selfballoon_min_usable_mb(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err)
return err;
if (val == 0)
return -EINVAL;
selfballoon_min_usable_mb = val;
return count;
}
static DEVICE_ATTR(selfballoon_min_usable_mb, S_IRUGO | S_IWUSR,
show_selfballoon_min_usable_mb,
store_selfballoon_min_usable_mb);
SELFBALLOON_SHOW(selfballoon_reserved_mb, "%d\n",
selfballoon_reserved_mb);
static ssize_t store_selfballoon_reserved_mb(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err)
return err;
if (val == 0)
return -EINVAL;
selfballoon_reserved_mb = val;
return count;
}
static DEVICE_ATTR(selfballoon_reserved_mb, S_IRUGO | S_IWUSR,
show_selfballoon_reserved_mb,
store_selfballoon_reserved_mb);
#ifdef CONFIG_FRONTSWAP
SELFBALLOON_SHOW(frontswap_selfshrinking, "%d\n", frontswap_selfshrinking);
static ssize_t store_frontswap_selfshrinking(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
bool was_enabled = frontswap_selfshrinking;
unsigned long tmp;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &tmp);
if (err)
return err;
if ((tmp != 0) && (tmp != 1))
return -EINVAL;
frontswap_selfshrinking = !!tmp;
if (!was_enabled && !xen_selfballooning_enabled &&
frontswap_selfshrinking)
schedule_delayed_work(&selfballoon_worker,
selfballoon_interval * HZ);
return count;
}
static DEVICE_ATTR(frontswap_selfshrinking, S_IRUGO | S_IWUSR,
show_frontswap_selfshrinking, store_frontswap_selfshrinking);
SELFBALLOON_SHOW(frontswap_inertia, "%d\n", frontswap_inertia);
static ssize_t store_frontswap_inertia(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err)
return err;
if (val == 0)
return -EINVAL;
frontswap_inertia = val;
frontswap_inertia_counter = val;
return count;
}
static DEVICE_ATTR(frontswap_inertia, S_IRUGO | S_IWUSR,
show_frontswap_inertia, store_frontswap_inertia);
SELFBALLOON_SHOW(frontswap_hysteresis, "%d\n", frontswap_hysteresis);
static ssize_t store_frontswap_hysteresis(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err)
return err;
if (val == 0)
return -EINVAL;
frontswap_hysteresis = val;
return count;
}
static DEVICE_ATTR(frontswap_hysteresis, S_IRUGO | S_IWUSR,
show_frontswap_hysteresis, store_frontswap_hysteresis);
#endif /* CONFIG_FRONTSWAP */
static struct attribute *selfballoon_attrs[] = {
&dev_attr_selfballooning.attr,
&dev_attr_selfballoon_interval.attr,
&dev_attr_selfballoon_downhysteresis.attr,
&dev_attr_selfballoon_uphysteresis.attr,
&dev_attr_selfballoon_min_usable_mb.attr,
&dev_attr_selfballoon_reserved_mb.attr,
#ifdef CONFIG_FRONTSWAP
&dev_attr_frontswap_selfshrinking.attr,
&dev_attr_frontswap_hysteresis.attr,
&dev_attr_frontswap_inertia.attr,
#endif
NULL
};
static const struct attribute_group selfballoon_group = {
.name = "selfballoon",
.attrs = selfballoon_attrs
};
#endif
int register_xen_selfballooning(struct device *dev)
{
int error = -1;
#ifdef CONFIG_SYSFS
error = sysfs_create_group(&dev->kobj, &selfballoon_group);
#endif
return error;
}
EXPORT_SYMBOL(register_xen_selfballooning);
int xen_selfballoon_init(bool use_selfballooning, bool use_frontswap_selfshrink)
{
bool enable = false;
unsigned long reserve_pages;
if (!xen_domain())
return -ENODEV;
if (xen_initial_domain()) {
pr_info("Xen selfballooning driver disabled for domain0\n");
return -ENODEV;
}
xen_selfballooning_enabled = tmem_enabled && use_selfballooning;
if (xen_selfballooning_enabled) {
pr_info("Initializing Xen selfballooning driver\n");
enable = true;
}
#ifdef CONFIG_FRONTSWAP
frontswap_selfshrinking = tmem_enabled && use_frontswap_selfshrink;
if (frontswap_selfshrinking) {
pr_info("Initializing frontswap selfshrinking driver\n");
enable = true;
}
#endif
if (!enable)
return -ENODEV;
/*
* Give selfballoon_reserved_mb a default value(10% of total ram pages)
* to make selfballoon not so aggressive.
*
* There are mainly two reasons:
* 1) The original goal_page didn't consider some pages used by kernel
* space, like slab pages and memory used by device drivers.
*
* 2) The balloon driver may not give back memory to guest OS fast
* enough when the workload suddenly aquries a lot of physical memory.
*
* In both cases, the guest OS will suffer from memory pressure and
* OOM killer may be triggered.
* By reserving extra 10% of total ram pages, we can keep the system
* much more reliably and response faster in some cases.
*/
if (!selfballoon_reserved_mb) {
reserve_pages = totalram_pages() / 10;
selfballoon_reserved_mb = PAGES2MB(reserve_pages);
}
schedule_delayed_work(&selfballoon_worker, selfballoon_interval * HZ);
return 0;
}
EXPORT_SYMBOL(xen_selfballoon_init);

10
include/xen/balloon.h
View File

@ -27,16 +27,6 @@ void balloon_set_new_target(unsigned long target);
int alloc_xenballooned_pages(int nr_pages, struct page **pages);
void free_xenballooned_pages(int nr_pages, struct page **pages);
struct device;
#ifdef CONFIG_XEN_SELFBALLOONING
extern int register_xen_selfballooning(struct device *dev);
#else
static inline int register_xen_selfballooning(struct device *dev)
{
return -ENOSYS;
}
#endif
#ifdef CONFIG_XEN_BALLOON
void xen_balloon_init(void);
#else

18
include/xen/tmem.h
View File

@ -1,18 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _XEN_TMEM_H
#define _XEN_TMEM_H
#include <linux/types.h>
#ifdef CONFIG_XEN_TMEM_MODULE
#define tmem_enabled true
#else
/* defined in drivers/xen/tmem.c */
extern bool tmem_enabled;
#endif
#ifdef CONFIG_XEN_SELFBALLOONING
extern int xen_selfballoon_init(bool, bool);
#endif
#endif /* _XEN_TMEM_H */