From: Andrew Morton <akpm@linux-foundation.org>
To: mm-commits@vger.kernel.org,tj@kernel.org,dennis@kernel.org,cl@gentwo.org,zenghongling@kylinos.cn,akpm@linux-foundation.org
Subject: [to-be-updated] mm-percpu-internalh-optimise-pcpu_chunk_struct-to-save-memory.patch removed from -mm tree
Date: Wed, 01 Apr 2026 16:58:29 -0700 [thread overview]
Message-ID: <20260401235830.6A5F7C116C6@smtp.kernel.org> (raw)
The quilt patch titled
Subject: mm/percpu-internal.h: optimise pcpu_chunk_struct to save memory
has been removed from the -mm tree. Its filename was
mm-percpu-internalh-optimise-pcpu_chunk_struct-to-save-memory.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: zenghongling <zenghongling@kylinos.cn>
Subject: mm/percpu-internal.h: optimise pcpu_chunk_struct to save memory
Date: Thu, 5 Mar 2026 15:30:43 +0800
The pcpu_chunk_struct has a hole of 4 bytes and pushes the struct to three
cachelines. Relocating the three booleans upwards allows for the struct
to only use two cachelines.
Before:
struct pcpu_chunk {
struct list_head list; /* 0 16 */
int free_bytes; /* 16 4 */
struct pcpu_block_md chunk_md; /* 20 32 */
/* XXX 4 bytes hole, try to pack */
long unsigned int * bound_map; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
void * base_addr __attribute__((__aligned__(64))); /* 64 8 */
long unsigned int * alloc_map; /* 72 8 */
struct pcpu_block_md * md_blocks; /* 80 8 */
void * data; /* 88 8 */
bool immutable; /* 96 1 */
bool isolated; /* 97 1 */
/* XXX 2 bytes hole, try to pack */
int start_offset; /* 100 4 */
int end_offset; /* 104 4 */
/* XXX 4 bytes hole, try to pack */
struct obj_cgroup * * obj_cgroups; /* 112 8 */
int nr_pages; /* 120 4 */
int nr_populated; /* 124 4 */
/* --- cacheline 2 boundary (128 bytes) --- */
int nr_empty_pop_pages; /* 128 4 */
/* XXX 4 bytes hole, try to pack */
long unsigned int populated[]; /* 136 0 */
/* size: 192, cachelines: 3, members: 17 */
/* sum members: 122, holes: 4, sum holes: 14 */
/* padding: 56 */
/* forced alignments: 1 */
} __attribute__((__aligned__(64)));
After:
struct pcpu_chunk {
struct list_head list; /* 0 16 */
int free_bytes; /* 16 4 */
struct pcpu_block_md chunk_md; /* 20 32 */
/* XXX 4 bytes hole, try to pack */
long unsigned int * bound_map; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
void * base_addr __attribute__((__aligned__(64))); /* 64 8 */
long unsigned int * alloc_map; /* 72 8 */
struct pcpu_block_md * md_blocks; /* 80 8 */
void * data; /* 88 8 */
bool immutable; /* 96 1 */
bool isolated; /* 97 1 */
/* XXX 2 bytes hole, try to pack */
int start_offset; /* 100 4 */
int end_offset; /* 104 4 */
int nr_empty_pop_pages; /* 108 4 */
struct obj_cgroup * * obj_cgroups; /* 112 8 */
int nr_pages; /* 120 4 */
int nr_populated; /* 124 4 */
/* --- cacheline 2 boundary (128 bytes) --- */
long unsigned int populated[]; /* 128 0 */
/* size: 128, cachelines: 2, members: 17 */
/* sum members: 122, holes: 2, sum holes: 6 */
/* forced alignments: 1 */
} __attribute__((__aligned__(64)));
Link: https://lkml.kernel.org/r/20260305073043.571691-1-zenghongling@kylinos.cn
Signed-off-by: zenghongling <zenghongling@kylinos.cn>
Cc: Christoph Lameter <cl@gentwo.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hongling Zeng <zenghongling@kylinos.cn>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/percpu-internal.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/percpu-internal.h~mm-percpu-internalh-optimise-pcpu_chunk_struct-to-save-memory
+++ a/mm/percpu-internal.h
@@ -77,13 +77,13 @@ struct pcpu_chunk {
int end_offset; /* additional area required to
have the region end page
aligned */
+ int nr_empty_pop_pages; /* # of empty populated pages */
#ifdef NEED_PCPUOBJ_EXT
struct pcpuobj_ext *obj_exts; /* vector of object cgroups */
#endif
int nr_pages; /* # of pages served by this chunk */
int nr_populated; /* # of populated pages */
- int nr_empty_pop_pages; /* # of empty populated pages */
unsigned long populated[]; /* populated bitmap */
};
_
Patches currently in -mm which might be from zenghongling@kylinos.cn are
reply other threads:[~2026-04-01 23:58 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260401235830.6A5F7C116C6@smtp.kernel.org \
--to=akpm@linux-foundation.org \
--cc=cl@gentwo.org \
--cc=dennis@kernel.org \
--cc=mm-commits@vger.kernel.org \
--cc=tj@kernel.org \
--cc=zenghongling@kylinos.cn \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox