* [PATCH v2] erofs: remove the fast path of per-CPU buffer decompression
@ 2021-10-14 6:39 Yue Hu
2021-10-14 6:49 ` Gao Xiang
0 siblings, 1 reply; 2+ messages in thread
From: Yue Hu @ 2021-10-14 6:39 UTC (permalink / raw)
To: xiang, chao, linux-erofs; +Cc: huyue2, zhangwen, linux-kernel, zbestahu
From: Yue Hu <huyue2@yulong.com>
As Xiang mentioned, such path has no real impact to our current
decompression strategy, remove it directly. Also, update the return
value of z_erofs_lz4_decompress() to 0 if success to keep consistent
with LZMA which will return 0 for that case.
Signed-off-by: Yue Hu <huyue2@yulong.com>
---
v2: just set ret = 0 in else branch and rearrange if statement into one line.
fs/erofs/decompressor.c | 63 +++++++------------------------------------------
1 file changed, 8 insertions(+), 55 deletions(-)
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 88e33ad..f8a372e 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -243,6 +243,8 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
if (ret >= 0)
memset(out + ret, 0, rq->outputsize - ret);
ret = -EIO;
+ } else {
+ ret = 0;
}
if (maptype == 0) {
@@ -269,33 +271,6 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
},
};
-static void copy_from_pcpubuf(struct page **out, const char *dst,
- unsigned short pageofs_out,
- unsigned int outputsize)
-{
- const char *end = dst + outputsize;
- const unsigned int righthalf = PAGE_SIZE - pageofs_out;
- const char *cur = dst - pageofs_out;
-
- while (cur < end) {
- struct page *const page = *out++;
-
- if (page) {
- char *buf = kmap_atomic(page);
-
- if (cur >= dst) {
- memcpy(buf, cur, min_t(uint, PAGE_SIZE,
- end - cur));
- } else {
- memcpy(buf + pageofs_out, cur + pageofs_out,
- min_t(uint, righthalf, end - cur));
- }
- kunmap_atomic(buf);
- }
- cur += PAGE_SIZE;
- }
-}
-
static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
struct list_head *pagepool)
{
@@ -306,34 +281,12 @@ static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
void *dst;
int ret;
- /* two optimized fast paths only for non bigpcluster cases yet */
- if (rq->inputsize <= PAGE_SIZE) {
- if (nrpages_out == 1 && !rq->inplace_io) {
- DBG_BUGON(!*rq->out);
- dst = kmap_atomic(*rq->out);
- dst_maptype = 0;
- goto dstmap_out;
- }
-
- /*
- * For the case of small output size (especially much less
- * than PAGE_SIZE), memcpy the decompressed data rather than
- * compressed data is preferred.
- */
- if (rq->outputsize <= PAGE_SIZE * 7 / 8) {
- dst = erofs_get_pcpubuf(1);
- if (IS_ERR(dst))
- return PTR_ERR(dst);
-
- rq->inplace_io = false;
- ret = alg->decompress(rq, dst);
- if (!ret)
- copy_from_pcpubuf(rq->out, dst, rq->pageofs_out,
- rq->outputsize);
-
- erofs_put_pcpubuf(dst);
- return ret;
- }
+ /* one optimized fast paths only for non bigpcluster cases yet */
+ if (rq->inputsize <= PAGE_SIZE && nrpages_out == 1 && !rq->inplace_io) {
+ DBG_BUGON(!*rq->out);
+ dst = kmap_atomic(*rq->out);
+ dst_maptype = 0;
+ goto dstmap_out;
}
/* general decoding path which can be used for all cases */
--
1.9.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] erofs: remove the fast path of per-CPU buffer decompression
2021-10-14 6:39 [PATCH v2] erofs: remove the fast path of per-CPU buffer decompression Yue Hu
@ 2021-10-14 6:49 ` Gao Xiang
0 siblings, 0 replies; 2+ messages in thread
From: Gao Xiang @ 2021-10-14 6:49 UTC (permalink / raw)
To: Yue Hu; +Cc: linux-kernel, zbestahu, huyue2, linux-erofs, zhangwen
On Thu, Oct 14, 2021 at 02:39:01PM +0800, Yue Hu wrote:
> From: Yue Hu <huyue2@yulong.com>
>
> As Xiang mentioned, such path has no real impact to our current
> decompression strategy, remove it directly. Also, update the return
> value of z_erofs_lz4_decompress() to 0 if success to keep consistent
> with LZMA which will return 0 for that case.
>
> Signed-off-by: Yue Hu <huyue2@yulong.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Thanks,
Gao Xiang
> ---
> v2: just set ret = 0 in else branch and rearrange if statement into one line.
>
> fs/erofs/decompressor.c | 63 +++++++------------------------------------------
> 1 file changed, 8 insertions(+), 55 deletions(-)
>
> diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
> index 88e33ad..f8a372e 100644
> --- a/fs/erofs/decompressor.c
> +++ b/fs/erofs/decompressor.c
> @@ -243,6 +243,8 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
> if (ret >= 0)
> memset(out + ret, 0, rq->outputsize - ret);
> ret = -EIO;
> + } else {
> + ret = 0;
> }
>
> if (maptype == 0) {
> @@ -269,33 +271,6 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
> },
> };
>
> -static void copy_from_pcpubuf(struct page **out, const char *dst,
> - unsigned short pageofs_out,
> - unsigned int outputsize)
> -{
> - const char *end = dst + outputsize;
> - const unsigned int righthalf = PAGE_SIZE - pageofs_out;
> - const char *cur = dst - pageofs_out;
> -
> - while (cur < end) {
> - struct page *const page = *out++;
> -
> - if (page) {
> - char *buf = kmap_atomic(page);
> -
> - if (cur >= dst) {
> - memcpy(buf, cur, min_t(uint, PAGE_SIZE,
> - end - cur));
> - } else {
> - memcpy(buf + pageofs_out, cur + pageofs_out,
> - min_t(uint, righthalf, end - cur));
> - }
> - kunmap_atomic(buf);
> - }
> - cur += PAGE_SIZE;
> - }
> -}
> -
> static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
> struct list_head *pagepool)
> {
> @@ -306,34 +281,12 @@ static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
> void *dst;
> int ret;
>
> - /* two optimized fast paths only for non bigpcluster cases yet */
> - if (rq->inputsize <= PAGE_SIZE) {
> - if (nrpages_out == 1 && !rq->inplace_io) {
> - DBG_BUGON(!*rq->out);
> - dst = kmap_atomic(*rq->out);
> - dst_maptype = 0;
> - goto dstmap_out;
> - }
> -
> - /*
> - * For the case of small output size (especially much less
> - * than PAGE_SIZE), memcpy the decompressed data rather than
> - * compressed data is preferred.
> - */
> - if (rq->outputsize <= PAGE_SIZE * 7 / 8) {
> - dst = erofs_get_pcpubuf(1);
> - if (IS_ERR(dst))
> - return PTR_ERR(dst);
> -
> - rq->inplace_io = false;
> - ret = alg->decompress(rq, dst);
> - if (!ret)
> - copy_from_pcpubuf(rq->out, dst, rq->pageofs_out,
> - rq->outputsize);
> -
> - erofs_put_pcpubuf(dst);
> - return ret;
> - }
> + /* one optimized fast paths only for non bigpcluster cases yet */
> + if (rq->inputsize <= PAGE_SIZE && nrpages_out == 1 && !rq->inplace_io) {
> + DBG_BUGON(!*rq->out);
> + dst = kmap_atomic(*rq->out);
> + dst_maptype = 0;
> + goto dstmap_out;
> }
>
> /* general decoding path which can be used for all cases */
> --
> 1.9.1
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