diff options
| author | Andrew Morton <akpm@osdl.org> | 2004-05-10 00:05:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2004-05-10 00:05:18 -0700 |
| commit | 2a12ed0ef2685626ad90736243747c9167535d82 (patch) | |
| tree | 4d8fe0da96d23c7bb81b4deb47533917ace1e6ba /mm | |
| parent | 6096781056dd1af176317798bbdafcd8c8c8a282 (diff) | |
| download | history-2a12ed0ef2685626ad90736243747c9167535d82.tar.gz | |
[PATCH] readahead: keep file->f_ra sane
When two threads are simultaneously pread()ing from the same fd (which is a
legitimate thing to do), the readahead code thinks that a huge amount of
seeking is happening and shrinks the window, damaging performance a lot.
I don't see a sane way to avoid this within the readahead code, so take a
private copy of the readahead state and restore it prior to returning from the
read.
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/filemap.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 1abe874e88e132..b7c98868c76a48 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -606,7 +606,7 @@ EXPORT_SYMBOL(grab_cache_page_nowait); * - note the struct file * is only passed for the use of readpage */ void do_generic_mapping_read(struct address_space *mapping, - struct file_ra_state *ra, + struct file_ra_state *_ra, struct file * filp, loff_t *ppos, read_descriptor_t * desc, @@ -616,6 +616,7 @@ void do_generic_mapping_read(struct address_space *mapping, unsigned long index, offset; struct page *cached_page; int error; + struct file_ra_state ra = *_ra; cached_page = NULL; index = *ppos >> PAGE_CACHE_SHIFT; @@ -638,13 +639,13 @@ void do_generic_mapping_read(struct address_space *mapping, } cond_resched(); - page_cache_readahead(mapping, ra, filp, index); + page_cache_readahead(mapping, &ra, filp, index); nr = nr - offset; find_page: page = find_get_page(mapping, index); if (unlikely(page == NULL)) { - handle_ra_miss(mapping, ra, index); + handle_ra_miss(mapping, &ra, index); goto no_cached_page; } if (!PageUptodate(page)) @@ -746,6 +747,8 @@ no_cached_page: goto readpage; } + *_ra = ra; + *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; if (cached_page) page_cache_release(cached_page); |