| Message ID | 1487609153-3367-1-git-send-email-artem.blagodarenko@gmail.com |
|---|---|
| State | Awaiting Upstream, archived |
| Headers | show |
On Mon, Feb 20, 2017 at 07:45:53PM +0300, Artem Blagodarenko wrote: > From: Andrew Perepechko <andrew.perepechko@seagate.com> > > With enabled meta_bg option block group descriptors > reading IO is not sequential and requires optimization. > > Signed-off-by: Andrew Perepechko <andrew.perepechko@seagate.com> > --- > fs/ext4/super.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index a673558..0e52c91 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -3879,6 +3879,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) > > bgl_lock_init(sbi->s_blockgroup_lock); > > + /* Pre-read the descriptors into the buffer cache */ > + for (i = 0; i < db_count; i++) { > + block = descriptor_loc(sb, logical_sb_block, i); > + sb_breadahead(sb, block); > + } Why does the libext2fs patch start readahead only on the meta bgs whereas this patch starts it for all of them? I suppose it's just as well that the kernel prefetches all of them, but I was curious. :) --D > + > for (i = 0; i < db_count; i++) { > block = descriptor_loc(sb, logical_sb_block, i); > sbi->s_group_desc[i] = sb_bread_unmovable(sb, block); > -- > 1.8.3.1 >
> 28 февр. 2017 г., в 19:19, Darrick J. Wong <darrick.wong@oracle.com> написал(а): > > On Mon, Feb 20, 2017 at 07:45:53PM +0300, Artem Blagodarenko wrote: >> From: Andrew Perepechko <andrew.perepechko@seagate.com> >> >> With enabled meta_bg option block group descriptors >> reading IO is not sequential and requires optimization. >> >> Signed-off-by: Andrew Perepechko <andrew.perepechko@seagate.com> >> --- >> fs/ext4/super.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/fs/ext4/super.c b/fs/ext4/super.c >> index a673558..0e52c91 100644 >> --- a/fs/ext4/super.c >> +++ b/fs/ext4/super.c >> @@ -3879,6 +3879,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) >> >> bgl_lock_init(sbi->s_blockgroup_lock); >> >> + /* Pre-read the descriptors into the buffer cache */ >> + for (i = 0; i < db_count; i++) { >> + block = descriptor_loc(sb, logical_sb_block, i); >> + sb_breadahead(sb, block); >> + } > > Why does the libext2fs patch start readahead only on the meta bgs > whereas this patch starts it for all of them? I suppose it's just as > well that the kernel prefetches all of them, but I was curious. :) > Just because a simplify code. libext2fs makes read a first gd porting via single read call, it fast. while just meta_bg generate a random io load. while a kernel part just a copy/paste a second loop :) Artem have a modified version for this patch, when sb_bread_unmovable moved into ext4_check_descriptors to have chance increase window between read-ahead call and access to the buffer. What about such change? > --D > >> + >> for (i = 0; i < db_count; i++) { >> block = descriptor_loc(sb, logical_sb_block, i); >> sbi->s_group_desc[i] = sb_bread_unmovable(sb, block); >> -- >> 1.8.3.1
On Mon, Feb 20, 2017 at 07:45:53PM +0300, Artem Blagodarenko wrote: > From: Andrew Perepechko <andrew.perepechko@seagate.com> > > With enabled meta_bg option block group descriptors > reading IO is not sequential and requires optimization. > > Signed-off-by: Andrew Perepechko <andrew.perepechko@seagate.com> Thanks, applied. - Ted
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index a673558..0e52c91 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3879,6 +3879,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) bgl_lock_init(sbi->s_blockgroup_lock); + /* Pre-read the descriptors into the buffer cache */ + for (i = 0; i < db_count; i++) { + block = descriptor_loc(sb, logical_sb_block, i); + sb_breadahead(sb, block); + } + for (i = 0; i < db_count; i++) { block = descriptor_loc(sb, logical_sb_block, i); sbi->s_group_desc[i] = sb_bread_unmovable(sb, block);