forked from Minki/linux
54b27f9287
Move (most of) the definitions of hashtab_search() and hashtab_insert()
to the header file. In combination with the previous patch, this avoids
calling the callbacks indirectly by function pointers and allows for
better optimization, leading to a drastic performance improvement of
these operations.
With this patch, I measured a speed up in the following areas (measured
on x86_64 F32 VM with 4 CPUs):
1. Policy load (`load_policy`) - takes ~150 ms instead of ~230 ms.
2. `chcon -R unconfined_u:object_r:user_tmp_t:s0:c381,c519 /tmp/linux-src`
where /tmp/linux-src is an extracted linux-5.7 source tarball -
takes ~522 ms instead of ~576 ms. This is because of many
symtab_search() calls in string_to_context_struct() when there are
many categories specified in the context.
3. `stress-ng --msg 1 --msg-ops 10000000` - takes 12.41 s instead of
13.95 s (consumes 18.6 s of kernel CPU time instead of 21.6 s).
This is thanks to security_transition_sid() being ~43% faster after
this patch.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
131 lines
2.8 KiB
C
131 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Implementation of the hash table type.
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*
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* Author : Stephen Smalley, <sds@tycho.nsa.gov>
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/errno.h>
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#include "hashtab.h"
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static struct kmem_cache *hashtab_node_cachep;
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/*
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* Here we simply round the number of elements up to the nearest power of two.
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* I tried also other options like rouding down or rounding to the closest
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* power of two (up or down based on which is closer), but I was unable to
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* find any significant difference in lookup/insert performance that would
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* justify switching to a different (less intuitive) formula. It could be that
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* a different formula is actually more optimal, but any future changes here
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* should be supported with performance/memory usage data.
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*
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* The total memory used by the htable arrays (only) with Fedora policy loaded
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* is approximately 163 KB at the time of writing.
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*/
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static u32 hashtab_compute_size(u32 nel)
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{
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return nel == 0 ? 0 : roundup_pow_of_two(nel);
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}
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int hashtab_init(struct hashtab *h, u32 nel_hint)
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{
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h->size = hashtab_compute_size(nel_hint);
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h->nel = 0;
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if (!h->size)
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return 0;
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h->htable = kcalloc(h->size, sizeof(*h->htable), GFP_KERNEL);
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return h->htable ? 0 : -ENOMEM;
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}
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int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
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void *key, void *datum)
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{
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struct hashtab_node *newnode;
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newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
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if (!newnode)
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return -ENOMEM;
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newnode->key = key;
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newnode->datum = datum;
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newnode->next = *dst;
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*dst = newnode;
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h->nel++;
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return 0;
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}
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void hashtab_destroy(struct hashtab *h)
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{
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u32 i;
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struct hashtab_node *cur, *temp;
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for (i = 0; i < h->size; i++) {
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cur = h->htable[i];
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while (cur) {
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temp = cur;
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cur = cur->next;
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kmem_cache_free(hashtab_node_cachep, temp);
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}
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h->htable[i] = NULL;
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}
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kfree(h->htable);
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h->htable = NULL;
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}
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int hashtab_map(struct hashtab *h,
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int (*apply)(void *k, void *d, void *args),
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void *args)
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{
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u32 i;
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int ret;
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struct hashtab_node *cur;
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for (i = 0; i < h->size; i++) {
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cur = h->htable[i];
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while (cur) {
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ret = apply(cur->key, cur->datum, args);
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if (ret)
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return ret;
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cur = cur->next;
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}
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}
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return 0;
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}
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void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
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{
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u32 i, chain_len, slots_used, max_chain_len;
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struct hashtab_node *cur;
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slots_used = 0;
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max_chain_len = 0;
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for (i = 0; i < h->size; i++) {
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cur = h->htable[i];
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if (cur) {
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slots_used++;
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chain_len = 0;
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while (cur) {
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chain_len++;
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cur = cur->next;
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}
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if (chain_len > max_chain_len)
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max_chain_len = chain_len;
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}
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}
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info->slots_used = slots_used;
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info->max_chain_len = max_chain_len;
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}
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void __init hashtab_cache_init(void)
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{
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hashtab_node_cachep = kmem_cache_create("hashtab_node",
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sizeof(struct hashtab_node),
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0, SLAB_PANIC, NULL);
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}
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