openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

mm/page_alloc: rename alloced to allocated 

Patch series "Introduce a bulk order-0 page allocator with two in-tree users", v6.

This series introduces a bulk order-0 page allocator with sunrpc and the
network page pool being the first users.  The implementation is not
efficient as semantics needed to be ironed out first.  If no other
semantic changes are needed, it can be made more efficient.  Despite that,
this is a performance-related for users that require multiple pages for an
operation without multiple round-trips to the page allocator.  Quoting the
last patch for the high-speed networking use-case

            Kernel          XDP stats       CPU     pps           Delta
            Baseline        XDP-RX CPU      total   3,771,046       n/a
            List            XDP-RX CPU      total   3,940,242    +4.49%
            Array           XDP-RX CPU      total   4,249,224   +12.68%

Via the SUNRPC traces of svc_alloc_arg()

	Single page: 25.007 us per call over 532,571 calls
	Bulk list:    6.258 us per call over 517,034 calls
	Bulk array:   4.590 us per call over 517,442 calls

Both potential users in this series are corner cases (NFS and high-speed
networks) so it is unlikely that most users will see any benefit in the
short term.  Other potential other users are batch allocations for page
cache readahead, fault around and SLUB allocations when high-order pages
are unavailable.  It's unknown how much benefit would be seen by
converting multiple page allocation calls to a single batch or what
difference it may make to headline performance.

Light testing of my own running dbench over NFS passed.  Chuck and Jesper
conducted their own tests and details are included in the changelogs.

Patch 1 renames a variable name that is particularly unpopular

Patch 2 adds a bulk page allocator

Patch 3 adds an array-based version of the bulk allocator

Patches 4-5 adds micro-optimisations to the implementation

Patches 6-7 SUNRPC user

Patches 8-9 Network page_pool user

This patch (of 9):

Review feedback of the bulk allocator twice found problems with "alloced"
being a counter for pages allocated.  The naming was based on the API name
"alloc" and was based on the idea that verbal communication about malloc
tends to use the fake word "malloced" instead of the fake word mallocated.
To be consistent, this preparation patch renames alloced to allocated in
rmqueue_bulk so the bulk allocator and per-cpu allocator use similar names
when the bulk allocator is introduced.

Link: https://lkml.kernel.org/r/20210325114228.27719-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20210325114228.27719-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2021-04-29 23:01:42 -07:00 committed by Linus Torvalds
parent 8f709dbdf9
commit cb66bede61
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
mm/page_alloc.c
View File

@ -2949,7 +2949,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
unsigned long count, struct list_head *list,
int migratetype, unsigned int alloc_flags)
{
int i, alloced = 0;
int i, allocated = 0;
spin_lock(&zone->lock);
for (i = 0; i < count; ++i) {
@ -2972,7 +2972,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
* pages are ordered properly.
*/
list_add_tail(&page->lru, list);
alloced++;
allocated++;
if (is_migrate_cma(get_pcppage_migratetype(page)))
__mod_zone_page_state(zone, NR_FREE_CMA_PAGES,
-(1 << order));
@ -2981,12 +2981,12 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
/*
* i pages were removed from the buddy list even if some leak due
* to check_pcp_refill failing so adjust NR_FREE_PAGES based
* on i. Do not confuse with 'alloced' which is the number of
* on i. Do not confuse with 'allocated' which is the number of
* pages added to the pcp list.
*/
__mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order));
spin_unlock(&zone->lock);
return alloced;
return allocated;
}
#ifdef CONFIG_NUMA