On 06/30, Nathan Chancellor wrote: > On Mon, Jun 29, 2020 at 01:27:20PM -0700, Jaegeuk Kim wrote: > > If two readahead threads having same offset enter in readpages, every read > > IOs are split and issued to the disk which giving lower bandwidth. > > > > This patch tries to avoid redundant readahead calls. > > > > Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org> > > --- > > v3: > > - use READ|WRITE_ONCE > > v2: > > - add missing code to bypass read > > > > fs/f2fs/data.c | 18 ++++++++++++++++++ > > fs/f2fs/f2fs.h | 1 + > > fs/f2fs/super.c | 2 ++ > > 3 files changed, 21 insertions(+) > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index 995cf78b23c5e..360b4c9080d97 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -2296,6 +2296,7 @@ static int f2fs_mpage_readpages(struct inode *inode, > > unsigned nr_pages = rac ? readahead_count(rac) : 1; > > unsigned max_nr_pages = nr_pages; > > int ret = 0; > > + bool drop_ra = false; > > > > map.m_pblk = 0; > > map.m_lblk = 0; > > @@ -2306,10 +2307,24 @@ static int f2fs_mpage_readpages(struct inode *inode, > > map.m_seg_type = NO_CHECK_TYPE; > > map.m_may_create = false; > > > > + /* > > + * Two readahead threads for same address range can cause race condition > > + * which fragments sequential read IOs. So let's avoid each other. > > + */ > > + if (rac && readahead_count(rac)) { > > + if (READ_ONCE(F2FS_I(inode)->ra_offset) == readahead_index(rac)) > > + drop_ra = true; > > + else > > + WRITE_ONCE(F2FS_I(inode)->ra_offset, > > + readahead_index(rac)); > > + } > > + > > for (; nr_pages; nr_pages--) { > > if (rac) { > > page = readahead_page(rac); > > prefetchw(&page->flags); > > + if (drop_ra) > > + goto next_page; > > When CONFIG_F2FS_FS_COMPRESSION is not set (i.e. x86_64 defconfig + > CONFIG_F2FS_FS=y): > > $ make -skj"$(nproc)" O=out distclean defconfig fs/f2fs/data.o > ../fs/f2fs/data.c: In function ‘f2fs_mpage_readpages’: > ../fs/f2fs/data.c:2327:5: error: label ‘next_page’ used but not defined > 2327 | goto next_page; > | ^~~~ > ...
Thanks. I pushed the fix for -next. https://lore.kernel.org/linux-f2fs-devel/1be18397-7fc6-703e-121b-e210e1013...@infradead.org/T/#t Thanks, > > Cheers, > Nathan > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel