[PATCH v2] erofs: relaxed temporary buffers allocation on readahead
Chunhai Guo
guochunhai at vivo.com
Mon Jan 22 14:49:34 AEDT 2024
On 2024/1/22 10:07, Gao Xiang wrote:
> [你通常不会收到来自 hsiangkao at linux.alibaba.com 的电子邮件。请访问 https://aka.ms/LearnAboutSenderIdentification，以了解这一点为什么很重要]
>
> On 2024/1/20 22:55, Chunhai Guo wrote:
>> Even with inplace decompression, sometimes extra temporary buffers are
>> still needed for decompression. In low-memory scenarios, it would be
>> better to try to allocate with GFP_NOWAIT on readahead first. That can
>> help reduce the time spent on page allocation under memory pressure.
>>
>> There is an average reduction of 21% in page allocation time under
> It would be better to add a table to show the absolute numbers too
> (like what you did in the global pool commit.) If it's possible, there
> is no need to send a update version for this, just reply the updated
> commit message and I will update the commit manually.
The table below shows detailed numbers. The reduction I mentioned before
was not accurate enough. Please help correct the improvement from 21% to
20.21%.
+--------------+----------------+---------------+---------+
| | w/o GFP_NOWAIT | w/ GFP_NOWAIT | diff |
+--------------+----------------+---------------+---------+
| Average (ms) | 3364 | 2684 | -20.21% |
+--------------+----------------+---------------+---------+
Thanks,
>
> Otherwise it looks good to me,
>
> Thanks,
> Gao Xiang
>
>> multi-app launch benchmark workload [1] on ARM64 Android devices running
>> the 5.15 kernel with an 8-core CPU and 8GB of memory.
>>
>> [1] https://lore.kernel.org/r/20240109074143.4138783-1-guochunhai@vivo.com
>>
>> Suggested-by: Gao Xiang <xiang at kernel.org>
>> Signed-off-by: Chunhai Guo <guochunhai at vivo.com>
>> ---
>> fs/erofs/compress.h | 5 ++---
>> fs/erofs/decompressor.c | 5 +++--
>> fs/erofs/decompressor_deflate.c | 19 +++++++++++++------
>> fs/erofs/decompressor_lzma.c | 17 ++++++++++++-----
>> fs/erofs/zdata.c | 16 ++++++++++++----
>> 5 files changed, 42 insertions(+), 20 deletions(-)
>>
>> diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
>> index 279933e007d2..7cc5841577b2 100644
>> --- a/fs/erofs/compress.h
>> +++ b/fs/erofs/compress.h
>> @@ -11,13 +11,12 @@
>> struct z_erofs_decompress_req {
>> struct super_block *sb;
>> struct page **in, **out;
>> -
>> unsigned short pageofs_in, pageofs_out;
>> unsigned int inputsize, outputsize;
>>
>> - /* indicate the algorithm will be used for decompression */
>> - unsigned int alg;
>> + unsigned int alg; /* the algorithm for decompression */
>> bool inplace_io, partial_decoding, fillgaps;
>> + gfp_t gfp; /* allocation flags for extra temporary buffers */
>> };
>>
>> struct z_erofs_decompressor {
>> diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
>> index 1d65b9f60a39..ef2b08ec9830 100644
>> --- a/fs/erofs/decompressor.c
>> +++ b/fs/erofs/decompressor.c
>> @@ -111,8 +111,9 @@ static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx,
>> victim = availables[--top];
>> get_page(victim);
>> } else {
>> - victim = erofs_allocpage(pagepool,
>> - GFP_KERNEL | __GFP_NOFAIL);
>> + victim = erofs_allocpage(pagepool, rq->gfp);
>> + if (!victim)
>> + return -ENOMEM;
>> set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
>> }
>> rq->out[i] = victim;
>> diff --git a/fs/erofs/decompressor_deflate.c b/fs/erofs/decompressor_deflate.c
>> index 4a64a9c91dd3..b98872058abe 100644
>> --- a/fs/erofs/decompressor_deflate.c
>> +++ b/fs/erofs/decompressor_deflate.c
>> @@ -95,7 +95,7 @@ int z_erofs_load_deflate_config(struct super_block *sb,
>> }
>>
>> int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
>> - struct page **pagepool)
>> + struct page **pgpl)
>> {
>> const unsigned int nrpages_out =
>> PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
>> @@ -158,8 +158,12 @@ int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
>> strm->z.avail_out = min_t(u32, outsz, PAGE_SIZE - pofs);
>> outsz -= strm->z.avail_out;
>> if (!rq->out[no]) {
>> - rq->out[no] = erofs_allocpage(pagepool,
>> - GFP_KERNEL | __GFP_NOFAIL);
>> + rq->out[no] = erofs_allocpage(pgpl, rq->gfp);
>> + if (!rq->out[no]) {
>> + kout = NULL;
>> + err = -ENOMEM;
>> + break;
>> + }
>> set_page_private(rq->out[no],
>> Z_EROFS_SHORTLIVED_PAGE);
>> }
>> @@ -211,8 +215,11 @@ int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
>>
>> DBG_BUGON(erofs_page_is_managed(EROFS_SB(sb),
>> rq->in[j]));
>> - tmppage = erofs_allocpage(pagepool,
>> - GFP_KERNEL | __GFP_NOFAIL);
>> + tmppage = erofs_allocpage(pgpl, rq->gfp);
>> + if (!tmppage) {
>> + err = -ENOMEM;
>> + goto failed;
>> + }
>> set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
>> copy_highpage(tmppage, rq->in[j]);
>> rq->in[j] = tmppage;
>> @@ -230,7 +237,7 @@ int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
>> break;
>> }
>> }
>> -
>> +failed:
>> if (zlib_inflateEnd(&strm->z) != Z_OK && !err)
>> err = -EIO;
>> if (kout)
>> diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c
>> index 2dd14f99c1dc..6ca357d83cfa 100644
>> --- a/fs/erofs/decompressor_lzma.c
>> +++ b/fs/erofs/decompressor_lzma.c
>> @@ -148,7 +148,7 @@ int z_erofs_load_lzma_config(struct super_block *sb,
>> }
>>
>> int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
>> - struct page **pagepool)
>> + struct page **pgpl)
>> {
>> const unsigned int nrpages_out =
>> PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
>> @@ -215,8 +215,11 @@ int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
>> PAGE_SIZE - pageofs);
>> outlen -= strm->buf.out_size;
>> if (!rq->out[no] && rq->fillgaps) { /* deduped */
>> - rq->out[no] = erofs_allocpage(pagepool,
>> - GFP_KERNEL | __GFP_NOFAIL);
>> + rq->out[no] = erofs_allocpage(pgpl, rq->gfp);
>> + if (!rq->out[no]) {
>> + err = -ENOMEM;
>> + break;
>> + }
>> set_page_private(rq->out[no],
>> Z_EROFS_SHORTLIVED_PAGE);
>> }
>> @@ -258,8 +261,11 @@ int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
>>
>> DBG_BUGON(erofs_page_is_managed(EROFS_SB(rq->sb),
>> rq->in[j]));
>> - tmppage = erofs_allocpage(pagepool,
>> - GFP_KERNEL | __GFP_NOFAIL);
>> + tmppage = erofs_allocpage(pgpl, rq->gfp);
>> + if (!tmppage) {
>> + err = -ENOMEM;
>> + goto failed;
>> + }
>> set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
>> copy_highpage(tmppage, rq->in[j]);
>> rq->in[j] = tmppage;
>> @@ -277,6 +283,7 @@ int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
>> break;
>> }
>> }
>> +failed:
>> if (no < nrpages_out && strm->buf.out)
>> kunmap(rq->out[no]);
>> if (ni < nrpages_in)
>> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
>> index 692c0c39be63..a293de2a60ed 100644
>> --- a/fs/erofs/zdata.c
>> +++ b/fs/erofs/zdata.c
>> @@ -82,6 +82,9 @@ struct z_erofs_pcluster {
>> /* L: indicate several pageofs_outs or not */
>> bool multibases;
>>
>> + /* L: whether extra buffer allocations are best-effort */
>> + bool besteffort;
>> +
>> /* A: compressed bvecs (can be cached or inplaced pages) */
>> struct z_erofs_bvec compressed_bvecs[];
>> };
>> @@ -964,7 +967,7 @@ static int z_erofs_read_fragment(struct super_block *sb, struct page *page,
>> }
>>
>> static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
>> - struct page *page)
>> + struct page *page, bool ra)
>> {
>> struct inode *const inode = fe->inode;
>> struct erofs_map_blocks *const map = &fe->map;
>> @@ -1014,6 +1017,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
>> err = z_erofs_pcluster_begin(fe);
>> if (err)
>> goto out;
>> + fe->pcl->besteffort |= !ra;
>> }
>>
>> /*
>> @@ -1280,7 +1284,11 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
>> .inplace_io = overlapped,
>> .partial_decoding = pcl->partial,
>> .fillgaps = pcl->multibases,
>> + .gfp = pcl->besteffort ?
>> + GFP_KERNEL | __GFP_NOFAIL :
>> + GFP_NOWAIT | __GFP_NORETRY
>> }, be->pagepool);
>> + pcl->besteffort = false;
>>
>> /* must handle all compressed pages before actual file pages */
>> if (z_erofs_is_inline_pcluster(pcl)) {
>> @@ -1785,7 +1793,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
>> if (PageUptodate(page))
>> unlock_page(page);
>> else
>> - (void)z_erofs_do_read_page(f, page);
>> + (void)z_erofs_do_read_page(f, page, !!rac);
>> put_page(page);
>> }
>>
>> @@ -1806,7 +1814,7 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
>> f.headoffset = (erofs_off_t)folio->index << PAGE_SHIFT;
>>
>> z_erofs_pcluster_readmore(&f, NULL, true);
>> - err = z_erofs_do_read_page(&f, &folio->page);
>> + err = z_erofs_do_read_page(&f, &folio->page, false);
>> z_erofs_pcluster_readmore(&f, NULL, false);
>> z_erofs_pcluster_end(&f);
>>
>> @@ -1847,7 +1855,7 @@ static void z_erofs_readahead(struct readahead_control *rac)
>> folio = head;
>> head = folio_get_private(folio);
>>
>> - err = z_erofs_do_read_page(&f, &folio->page);
>> + err = z_erofs_do_read_page(&f, &folio->page, true);
>> if (err && err != -EINTR)
>> erofs_err(inode->i_sb, "readahead error at folio %lu @ nid %llu",
>> folio->index, EROFS_I(inode)->nid);
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