On Fri, 26 Jan 2024 13:36:16 +0800 Gao Xiang <[email protected]> wrote:
> From: Chunhai Guo <[email protected]> > > Even with inplace decompression, sometimes very few temporary buffers > are still needed for a single decompression shot (e.g. 16 pages for 64k > sliding window or 4 pages for 16k sliding window). 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 durative memory pressure. > > Here are detailed performance numbers under multi-app launch benchmark > workload [1] on ARM64 Android devices (8-core CPU and 8GB of memory) > running a 5.15 LTS kernel with EROFS of 4k pclusters: > > +----------------+---------+---------+---------+ > | LZ4 | vanilla | patched | diff | > |----------------+---------+---------+---------| > | Average (ms) | 3364 | 2684 | -20.21% | [64k sliding window] > |----------------+---------+---------+---------| > | Average (ms) | 2079 | 1610 | -22.56% | [16k sliding window] > +----------------+---------+---------+---------+ > > The total size of system images for 4k pcluster is almost unchanged: > (64k sliding window) 9,117,044 KB > (16k sliding window) 9,113,096 KB > > Therefore, in addition to switch the sliding window from 64k to 16k, > after applying this patch, it can eventually save 52.14% (3364 -> 1610) > on average with no memory reservation. That is particularly useful for > embedded devices with limited resources. > > [1] https://lore.kernel.org/r/[email protected] > > Suggested-by: Gao Xiang <[email protected]> > Signed-off-by: Chunhai Guo <[email protected]> > Signed-off-by: Gao Xiang <[email protected]> > --- > v2: https://lore.kernel.org/r/[email protected] > change since v2: > - update commit message according to test results. > > I plan to apply this version. > > 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 072ef6a66823..d4cee95af14c 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 c1c77166b30f..1d0fdc145fd6 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[]; > }; > @@ -960,7 +963,7 @@ 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; > @@ -1010,6 +1013,7 @@ 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; > } > > /* > @@ -1276,7 +1280,11 @@ 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; reposition it following `pcl->multibases = false`? > > /* must handle all compressed pages before actual file pages */ > if (z_erofs_is_inline_pcluster(pcl)) { > @@ -1787,7 +1795,7 @@ 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); > } > > @@ -1808,7 +1816,7 @@ 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); > > @@ -1849,7 +1857,7 @@ 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);
