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author | Gao Xiang <hsiangkao@redhat.com> | 2021-03-21 21:32:27 +0300 |
---|---|---|
committer | Gao Xiang <hsiangkao@redhat.com> | 2021-03-29 05:18:01 +0300 |
commit | 0b964600d3aae56ff9d5bdd710a79f39a44c572c (patch) | |
tree | 550634ce6fb92373b5691fbf2c5b5b7660ca6847 /fs/erofs | |
parent | 30048cdac4b92f39ee50e2a1344f5899f8e70cb6 (diff) | |
download | linux-0b964600d3aae56ff9d5bdd710a79f39a44c572c.tar.xz |
erofs: complete a missing case for inplace I/O
Add a missing case which could cause unnecessary page allocation but
not directly use inplace I/O instead, which increases runtime extra
memory footprint.
The detail is, considering an online file-backed page, the right half
of the page is chosen to be cached (e.g. the end page of a readahead
request) and some of its data doesn't exist in managed cache, so the
pcluster will be definitely kept in the submission chain. (IOWs, it
cannot be decompressed without I/O, e.g., due to the bypass queue).
Currently, DELAYEDALLOC/TRYALLOC cases can be downgraded as NOINPLACE,
and stop online pages from inplace I/O. After this patch, unneeded page
allocations won't be observed in pickup_page_for_submission() then.
Link: https://lore.kernel.org/r/20210321183227.5182-1-hsiangkao@aol.com
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Diffstat (limited to 'fs/erofs')
-rw-r--r-- | fs/erofs/zdata.c | 44 |
1 files changed, 29 insertions, 15 deletions
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 7ab8a4e3dfcb..cd9b76216925 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -104,6 +104,12 @@ enum z_erofs_collectmode { * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________| */ COLLECT_PRIMARY_HOOKED, + /* + * a weak form of COLLECT_PRIMARY_FOLLOWED, the difference is that it + * could be dispatched into bypass queue later due to uptodated managed + * pages. All related online pages cannot be reused for inplace I/O (or + * pagevec) since it can be directly decoded without I/O submission. + */ COLLECT_PRIMARY_FOLLOWED_NOINPLACE, /* * The current collection has been linked with the owned chain, and @@ -186,21 +192,25 @@ static void preload_compressed_pages(struct z_erofs_collector *clt, if (page) { t = tag_compressed_page_justfound(page); - } else if (type == DELAYEDALLOC) { - t = tagptr_init(compressed_page_t, PAGE_UNALLOCATED); - } else if (type == TRYALLOC) { - newpage = erofs_allocpage(pagepool, gfp); - if (!newpage) - goto dontalloc; - - set_page_private(newpage, Z_EROFS_PREALLOCATED_PAGE); - t = tag_compressed_page_justfound(newpage); - } else { /* DONTALLOC */ -dontalloc: - if (standalone) - clt->compressedpages = pages; + } else { + /* I/O is needed, no possible to decompress directly */ standalone = false; - continue; + switch (type) { + case DELAYEDALLOC: + t = tagptr_init(compressed_page_t, + PAGE_UNALLOCATED); + break; + case TRYALLOC: + newpage = erofs_allocpage(pagepool, gfp); + if (!newpage) + continue; + set_page_private(newpage, + Z_EROFS_PREALLOCATED_PAGE); + t = tag_compressed_page_justfound(newpage); + break; + default: /* DONTALLOC */ + continue; + } } if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t))) @@ -214,7 +224,11 @@ dontalloc: } } - if (standalone) /* downgrade to PRIMARY_FOLLOWED_NOINPLACE */ + /* + * don't do inplace I/O if all compressed pages are available in + * managed cache since it can be moved to the bypass queue instead. + */ + if (standalone) clt->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE; } |