[PATCH v2] erofs: relaxed temporary buffers allocation on readahead
Chunhai Guo
guochunhai at vivo.com
Fri Jan 26 13:41:50 AEDT 2024
On 2024/1/22 15:42, Chunhai Guo wrote:
> On 2024/1/22 12:37, 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 2024/1/22 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
> The result is tested with 64k sliding window change.
>
>> 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.
>
> OK. I will reply to this email when the benchmark is finished.
The benchmark has been completed and the table below shows that there is
an average 52.14% reduction in page allocation time with these two
optimizations.
+--------------+----------------+---------------+---------+ | | 64k
window | 16k window | | | | w/o GFP_NOWAIT | w/ GFP_NOWAIT | diff |
+--------------+----------------+---------------+---------+ | Average
(ms) | 3364 | 1610 | -52.14% |
+--------------+----------------+---------------+---------+
Table below summarizes the results of these three benchmarks.
+--------------+----------------+----------------+---------------+---------------+
| | 64k window | 16k window | 64k window | 16k
window |
| | w/o GFP_NOWAIT | w/o GFP_NOWAIT | w/ GFP_NOWAIT | w/
GFP_NOWAIT |
+--------------+----------------+----------------+---------------+---------------+
| Average (ms) | 3364 | 2079 | 2684 |
1610 |
+--------------+----------------+----------------+---------------+---------------+
| diff | | -38.19% | -20.81% |
-52.14% |
+--------------+----------------+----------------+---------------+---------------+
Thanks.
>> 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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