[PATCH v2] erofs: relaxed temporary buffers allocation on readahead
Gao Xiang
hsiangkao at linux.alibaba.com
Mon Jan 22 15:37:01 AEDT 2024
On 2024/1/22 11:49, Chunhai Guo wrote:
> 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% |
> +--------------+----------------+---------------+---------+
Did it test without the 16k sliding window change?
https://lore.kernel.org/linux-erofs/69711d55-f7a2-420b-9ba8-fa2921f66a4c@vivo.com
Could you benchmark these two optimizations together to
show the extreme optimized case without a global pool?
With a new table if possible? I will add this to
the commit message too.
Thanks,
Gao Xiang
>
> 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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