The patch titled
Subject: crypto: scompress: remove memcpy if sg_nents is 1
has been added to the -mm mm-unstable branch. Its filename is
crypto-scompress-remove-memcpy-if-sg_nents-is-1.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/crypto-scompress-remove-memcpy-if-sg_nents-is-1.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Barry Song <v-songbaohua@xxxxxxxx>
Subject: crypto: scompress: remove memcpy if sg_nents is 1
Date: Sat, 17 Feb 2024 17:51:02 +1300
while sg_nents is 1 which is always true for the current kernel as the
only user - zswap is the case, we should remove two big memcpy.
Link: https://lkml.kernel.org/r/20240217045102.55339-4-21cnbao@xxxxxxxxx
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
Tested-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Cc: Chris Li <chrisl@xxxxxxxxxx>
Cc: Dan Streetman <ddstreet@xxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Seth Jennings <sjenning@xxxxxxxxxx>
Cc: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
crypto/scompress.c | 36 +++++++++++++++++++++++++++++-------
1 file changed, 29 insertions(+), 7 deletions(-)
--- a/crypto/scompress.c~crypto-scompress-remove-memcpy-if-sg_nents-is-1
+++ a/crypto/scompress.c
@@ -117,6 +117,7 @@ static int scomp_acomp_comp_decomp(struc
struct crypto_scomp *scomp = *tfm_ctx;
void **ctx = acomp_request_ctx(req);
struct scomp_scratch *scratch;
+ void *src, *dst;
unsigned int dlen;
int ret;
@@ -134,13 +135,25 @@ static int scomp_acomp_comp_decomp(struc
scratch = raw_cpu_ptr(&scomp_scratch);
spin_lock(&scratch->lock);
- scatterwalk_map_and_copy(scratch->src, req->src, 0, req->slen, 0);
+ if (sg_nents(req->src) == 1) {
+ src = kmap_local_page(sg_page(req->src)) + req->src->offset;
+ } else {
+ scatterwalk_map_and_copy(scratch->src, req->src, 0,
+ req->slen, 0);
+ src = scratch->src;
+ }
+
+ if (req->dst && sg_nents(req->dst) == 1)
+ dst = kmap_local_page(sg_page(req->dst)) + req->dst->offset;
+ else
+ dst = scratch->dst;
+
if (dir)
- ret = crypto_scomp_compress(scomp, scratch->src, req->slen,
- scratch->dst, &req->dlen, *ctx);
+ ret = crypto_scomp_compress(scomp, src, req->slen,
+ dst, &req->dlen, *ctx);
else
- ret = crypto_scomp_decompress(scomp, scratch->src, req->slen,
- scratch->dst, &req->dlen, *ctx);
+ ret = crypto_scomp_decompress(scomp, src, req->slen,
+ dst, &req->dlen, *ctx);
if (!ret) {
if (!req->dst) {
req->dst = sgl_alloc(req->dlen, GFP_ATOMIC, NULL);
@@ -152,10 +165,19 @@ static int scomp_acomp_comp_decomp(struc
ret = -ENOSPC;
goto out;
}
- scatterwalk_map_and_copy(scratch->dst, req->dst, 0, req->dlen,
- 1);
+ if (dst == scratch->dst) {
+ scatterwalk_map_and_copy(scratch->dst, req->dst, 0,
+ req->dlen, 1);
+ } else {
+ flush_dcache_page(sg_page(req->dst));
+ }
}
out:
+ if (src != scratch->src)
+ kunmap_local(src);
+ if (dst != scratch->dst)
+ kunmap_local(dst);
+
spin_unlock(&scratch->lock);
return ret;
}
_
Patches currently in -mm which might be from v-songbaohua@xxxxxxxx are
zram-do-not-allocate-physically-contiguous-strm-buffers.patch
crypto-introduce-acomp_is_sleepable-to-expose-if-comp-drivers-might-sleep.patch
mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch
crypto-scompress-remove-memcpy-if-sg_nents-is-1.patch
