From: Dominique Martinet <asmadeus@codewreck.org>
To: Eric Van Hensbergen <ericvh@kernel.org>,
Latchesar Ionkov <lucho@ionkov.net>,
Dominique Martinet <asmadeus@codewreck.org>,
Christian Schoenebeck <linux_oss@crudebyte.com>
Cc: v9fs@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: [PATCH] 9p: optimize p9_fcall struct
Date: Thu, 29 Oct 2026 06:00:12 +0000 [thread overview]
Message-ID: <20261029060014.3-1-asmadeus@codewreck.org> (raw)
p9_fcall has a 1 byte hole followed by more data and then a single byte
element:
struct p9_fcall {
u32 size; /* 0 4 */
u8 id; /* 4 1 */
/* XXX 1 byte hole, try to pack */
u16 tag; /* 6 2 */
size_t offset; /* 8 8 */
size_t capacity; /* 16 8 */
struct kmem_cache * cache; /* 24 8 */
u8 * sdata; /* 32 8 */
bool zc; /* 40 1 */
/* size: 48, cachelines: 1, members: 8 */
/* sum members: 40, holes: 1, sum holes: 1 */
/* padding: 7 */
/* last cacheline: 48 bytes */
};
move `zc` up to optimize it:
struct p9_fcall {
u32 size; /* 0 4 */
u8 id; /* 4 1 */
bool zc; /* 5 1 */
u16 tag; /* 6 2 */
size_t offset; /* 8 8 */
size_t capacity; /* 16 8 */
struct kmem_cache * cache; /* 24 8 */
u8 * sdata; /* 32 8 */
/* size: 40, cachelines: 1, members: 8 */
/* last cacheline: 40 bytes */
};
This in turn also makes p9_req_t 16 bytes smaller (152 -> 136) as it
contains two of these.
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
---
include/net/9p/9p.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
index 22ab7486795d..067e8a3b38d0 100644
--- a/include/net/9p/9p.h
+++ b/include/net/9p/9p.h
@@ -581,6 +581,7 @@ struct p9_rstatfs {
struct p9_fcall {
u32 size;
u8 id;
+ bool zc;
u16 tag;
size_t offset;
@@ -588,7 +589,6 @@ struct p9_fcall {
struct kmem_cache *cache;
u8 *sdata;
- bool zc;
};
int p9_errstr2errno(char *errstr, int len);
--
2.56.0
reply other threads:[~2026-10-29 6:00 UTC|newest]
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