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NeilBrown bf701b765e NFS: switch nfsiod to be an UNBOUND workqueue.
nfsiod is currently a concurrency-managed workqueue (CMWQ).
This means that workitems scheduled to nfsiod on a given CPU are queued
behind all other work items queued on any CMWQ on the same CPU.  This
can introduce unexpected latency.

Occaionally nfsiod can even cause excessive latency.  If the work item
to complete a CLOSE request calls the final iput() on an inode, the
address_space of that inode will be dismantled.  This takes time
proportional to the number of in-memory pages, which on a large host
working on large files (e.g..  5TB), can be a large number of pages
resulting in a noticable number of seconds.

We can avoid these latency problems by switching nfsiod to WQ_UNBOUND.
This causes each concurrent work item to gets a dedicated thread which
can be scheduled to an idle CPU.

There is precedent for this as several other filesystems use WQ_UNBOUND
workqueue for handling various async events.

Signed-off-by: NeilBrown <neilb@suse.de>
Fixes: ada609ee2a ("workqueue: use WQ_MEM_RECLAIM instead of WQ_RESCUER")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2020-12-02 14:05:54 -05:00
arch Yet two more places which invoke tracing from RCU disabled regions in the 2020-11-29 11:19:26 -08:00
block block/keyslot-manager: prevent crash when num_slots=1 2020-11-20 11:52:52 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto drivers-5.10-2020-10-12 2020-10-13 13:04:41 -07:00
Documentation Kbuild fixes for v5.10 2020-11-28 10:42:30 -08:00
drivers Yet two more places which invoke tracing from RCU disabled regions in the 2020-11-29 11:19:26 -08:00
fs NFS: switch nfsiod to be an UNBOUND workqueue. 2020-12-02 14:05:54 -05:00
include SUNRPC: Remove unused function xprt_load_transport() 2020-12-02 14:05:53 -05:00
init Urgent printk fix for 5.10 2020-11-27 10:38:36 -08:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel Yet two more places which invoke tracing from RCU disabled regions in the 2020-11-29 11:19:26 -08:00
lib lib/strncpy_from_user.c: Mask out bytes after NUL terminator. 2020-11-19 11:56:16 -08:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm: fix VM_BUG_ON(PageTail) and BUG_ON(PageWriteback) 2020-11-24 15:23:19 -08:00
net net: sunrpc: Fix 'snprintf' return value check in 'do_xprt_debugfs' 2020-12-02 14:05:54 -05:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2020-11-06 17:49:34 -08:00
scripts Kbuild fixes for v5.10 2020-11-28 10:42:30 -08:00
security selinux/stable-5.10 PR 20201113 2020-11-14 12:04:02 -08:00
sound ASoC: Fixes for v5.11 2020-11-19 19:56:29 +01:00
tools perf probe: Change function definition check due to broken DWARF 2020-11-27 14:36:15 -03:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt kvm: x86/mmu: Support dirty logging for the TDP MMU 2020-10-23 03:42:13 -04:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap ARM: 2020-11-27 11:04:13 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Samsung changes for v5.10 2020-11-13 13:16:27 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Char/misc driver fixes for 5.10-rc6 2020-11-28 10:04:36 -08:00
Makefile Linux 5.10-rc6 2020-11-29 15:50:50 -08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.