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Date: Wed, 13 Jan 2016 14:57:37 +0800
From: Chao Yu <chao2.yu@...sung.com>
To: 'Jaegeuk Kim' <jaegeuk@...nel.org>
Cc: linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: RE: [f2fs-dev] [RFC PATCH 2/2] f2fs: export a threshold in sysfs for
controlling dio serialization
Hi Jaegeuk,
> -----Original Message-----
> From: Chao Yu [mailto:chao2.yu@...sung.com]
> Sent: Tuesday, December 29, 2015 2:39 PM
> To: 'Jaegeuk Kim'
> Cc: linux-kernel@...r.kernel.org; linux-f2fs-devel@...ts.sourceforge.net
> Subject: Re: [f2fs-dev] [RFC PATCH 2/2] f2fs: export a threshold in sysfs for controlling dio
> serialization
>
> Hi Jaegeuk,
>
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk@...nel.org]
> > Sent: Tuesday, December 29, 2015 6:52 AM
> > To: Chao Yu
> > Cc: linux-f2fs-devel@...ts.sourceforge.net; linux-kernel@...r.kernel.org
> > Subject: Re: [RFC PATCH 2/2] f2fs: export a threshold in sysfs for controlling dio serialization
> >
> > Hi Chao,
> >
> > On Mon, Dec 28, 2015 at 06:05:45PM +0800, Chao Yu wrote:
> > > As Yunlei He reported when he test with the patch ("f2fs: enhance
> > > multithread dio write performance"):
> > > "Does share writepages mutex lock have an effect on cache write?
> > > Here is AndroBench result on my phone:
> > >
> > > Before patch:
> > > 1R1W 8R8W 16R16W
> > > Sequential Write 161.31 163.85 154.67
> > > Random Write 9.48 17.66 18.09
> > >
> > > After patch:
> > > 1R1W 8R8W 16R16W
> > > Sequential Write 159.61 157.24 160.11
> > > Random Write 9.17 8.51 8.8
> > >
> > > Unit:Mb/s, File size: 64M, Buffer size: 4k"
> > >
> > > The turth is androidbench uses single thread with dio write to test performance
> > > of sequential write, and use multi-threads with dio write to test performance
> > > of random write. so we can not see any improvement in sequentail write test
> > > since serializing dio page allocation can only improve performance in
> > > multi-thread scenario, and there is a regression in multi-thread test with 4k
> > > dio write, this is because grabbing sbi->writepages lock for serializing block
> > > allocation stop the concurrency, so that less small dio bios could be merged,
> > > moreover, when there are huge number of small dio writes, grabbing mutex lock
> > > per dio increases the overhead.
> > >
> > > After all, serializing dio could only be used for concurrent scenario of
> > > big dio, so this patch introduces a threshold in sysfs to provide user the
> > > interface of defining 'a big dio' with specified page number, which could
> > > be used to control wthether serialize or not that kind of dio with specified
> > > page number.
> >
> > Can you merge two patches together?
>
> OK.
>
> >
> > And, if this is correct, can we investigate the lock effect in
> > f2fs_write_data_pages too?
> >
> > What if we add a condition for the lock like this?
> >
> > if (get_dirty_pages(inode) > serialzed_pages)
> > mutex_lock();
>
> Agreed, I will investigate it.
Sorry for the delay.
I have did some tests with following modification as you mentioned, but
sadly it causes a performance regression.
As blktrace & blkiomon shows, there are more small size reqs submitted from
block layer if we do not serialize IOs, I guess that would be the main reason
of regression.
a) OPU
Test #1:
Environmemt: note4 emmc
fio --name randw --ioengine=sync --invalidate=1 --rw=randwrite --randseed=2015 --directory=/data/test/dir/ --filesize=256m
--size=16m --bsrang=32k-1024k --direct=0 --numjobs=32 --fsync=1 --end_fsync=1
serialize all serialize partial serialize none
threshold 0 64 256
1 27121 24922 23491
2 25664 25165 22828
3 27426 24916 24609
4 31871 25046 22410
5 26304 25747 22410
average 27677.2 25159.2 23149.6
Unit: KB/s
Test #2:
Environmemt: 4GB zram
time fs_mark -t 16 -L 1 -s 8192 -S 1 -d /mnt/f2fs/
-s threshold no serialization serialization
4096 1 1.582 1.547
8192 2 1.632 1.669
16384 4 1.577 1.491
32768 8 1.560 1.551
65536 16 1.984 1.849
131072 32 3.590 3.347
262144 64 6.360 5.352
524288 128 6.502 4.668
1048576 256 6.518 4.488
2097152 512 6.422 4.717
Unit: second
b) IPU
fio --name randw --ioengine=sync --invalidate=1 --rw=randwrite --randseed=2015 --directory=/data/test/dir/ --filesize=16m --size=16m
--bsrang=32k-1024k --direct=0 --numjobs=32 --fdatasync=1 --end_fsync=1
fio --name randw --ioengine=sync --invalidate=1 --rw=write --directory=/data/test/dir/ --filesize=16m --size=16m --bs=2m --direct=0
--numjobs=32
serialize all serialize partial serialize none
threshold 0 64 256
1 35763 33649 33124
2 39304 35097 33326
3 35731 33956 32405
4 33855 33943 36890
5 33857 33881 35128
average 35702 34105.2 34174.6
Unit: KB/s
---
fs/f2fs/data.c | 6 ++++--
fs/f2fs/f2fs.h | 2 ++
fs/f2fs/super.c | 3 +++
3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 1c5c5c3..29f2a91 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1365,8 +1365,10 @@ static int f2fs_write_data_pages(struct address_space *mapping,
diff = nr_pages_to_write(sbi, DATA, wbc);
if (!S_ISDIR(inode->i_mode)) {
- mutex_lock(&sbi->writepages);
- locked = true;
+ if (get_dirty_pages(inode) > sbi->serialized_buf_pages) {
+ mutex_lock(&sbi->writepages);
+ locked = true;
+ }
}
ret = f2fs_write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);
f2fs_submit_merged_bio(sbi, DATA, WRITE);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 4a89f19..e608c62 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -336,6 +336,7 @@ enum {
#define MAX_DIR_RA_PAGES 4 /* maximum ra pages of dir */
#define DEF_SERIALIZED_DIO_PAGES 64 /* default serialized dio pages */
+#define DEF_SERIALIZED_BUF_PAGES 64 /* default serialized buf pages */
/* vector size for gang look-up from extent cache that consists of radix tree */
#define EXT_TREE_VEC_SIZE 64
@@ -798,6 +799,7 @@ struct f2fs_sb_info {
int active_logs; /* # of active logs */
int dir_level; /* directory level */
int serialized_dio_pages; /* serialized direct IO pages */
+ int serialized_buf_pages; /* serialized buffered IO pages */
block_t user_block_count; /* # of user blocks */
block_t total_valid_block_count; /* # of valid blocks */
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 9e0e80d..f7d8e51c 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -221,6 +221,7 @@ F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, dir_level, dir_level);
F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, cp_interval, interval_time[CP_TIME]);
F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, idle_interval, interval_time[REQ_TIME]);
F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, serialized_dio_pages, serialized_dio_pages);
+F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, serialized_buf_pages, serialized_buf_pages);
#define ATTR_LIST(name) (&f2fs_attr_##name.attr)
static struct attribute *f2fs_attrs[] = {
@@ -237,6 +238,7 @@ static struct attribute *f2fs_attrs[] = {
ATTR_LIST(max_victim_search),
ATTR_LIST(dir_level),
ATTR_LIST(serialized_dio_pages),
+ ATTR_LIST(serialized_buf_pages),
ATTR_LIST(ram_thresh),
ATTR_LIST(ra_nid_pages),
ATTR_LIST(cp_interval),
@@ -1129,6 +1131,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
sbi->interval_time[CP_TIME] = DEF_CP_INTERVAL;
sbi->interval_time[REQ_TIME] = DEF_IDLE_INTERVAL;
sbi->serialized_dio_pages = DEF_SERIALIZED_DIO_PAGES;
+ sbi->serialized_buf_pages = DEF_SERIALIZED_BUF_PAGES;
clear_sbi_flag(sbi, SBI_NEED_FSCK);
INIT_LIST_HEAD(&sbi->s_list);
--
2.6.3
Then I did a quick test in zram by using fs_mark with following method:
1) use blk_plug in ->writepages;
2) decrease granularity of sbi->writepages: for user defined small IOs, we
move sbi->writepages into do_write_page.
Unfortunately, also cause a regression. So I'm still looking for the right
way to improve concurrency with small impaction on performance.
BTW, for IPU, no serialization affects lesser on performance, maybe we could
try:
if (!need_ipu || holes_exist_in_file)
mutex_lock(&sbi->writepages);
Thanks,
>
> Thanks,
>
> >
> > Thanks,
> >
> > >
> > > Though, this is only RFC patch since the optimization works in rare scenario.
> > >
> > > Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> > > ---
> > > Documentation/ABI/testing/sysfs-fs-f2fs | 12 ++++++++++++
> > > fs/f2fs/data.c | 3 ++-
> > > fs/f2fs/f2fs.h | 3 +++
> > > fs/f2fs/super.c | 3 +++
> > > 4 files changed, 20 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs
> > b/Documentation/ABI/testing/sysfs-fs-f2fs
> > > index 0345f2d..560a4f1 100644
> > > --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> > > +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> > > @@ -92,3 +92,15 @@ Date: October 2015
> > > Contact: "Chao Yu" <chao2.yu@...sung.com>
> > > Description:
> > > Controls the count of nid pages to be readaheaded.
> > > +
> > > +What: /sys/fs/f2fs/<disk>/serialized_dio_pages
> > > +Date: December 2015
> > > +Contact: "Chao Yu" <chao2.yu@...sung.com>
> > > +Description:
> > > + It is a threshold with the unit of page size.
> > > + If DIO page count is equal or big than the threshold,
> > > + whole process of block address allocation of dio pages
> > > + will become atomic like buffered write.
> > > + It is used to maximize bandwidth utilization in the
> > > + scenario of concurrent write with dio vs buffered or
> > > + dio vs dio.
> > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > > index 6b24446..abcd100 100644
> > > --- a/fs/f2fs/data.c
> > > +++ b/fs/f2fs/data.c
> > > @@ -1660,7 +1660,8 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter
> *iter,
> > > trace_f2fs_direct_IO_enter(inode, offset, count, rw);
> > >
> > > if (rw == WRITE) {
> > > - bool serialized = (F2FS_BYTES_TO_BLK(count) >= 64);
> > > + bool serialized = (F2FS_BYTES_TO_BLK(count) >=
> > > + sbi->serialized_dio_pages);
> > >
> > > if (serialized)
> > > mutex_lock(&sbi->writepages);
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > index 3406e99..8f35dd7 100644
> > > --- a/fs/f2fs/f2fs.h
> > > +++ b/fs/f2fs/f2fs.h
> > > @@ -333,6 +333,8 @@ enum {
> > >
> > > #define MAX_DIR_RA_PAGES 4 /* maximum ra pages of dir */
> > >
> > > +#define DEF_SERIALIZED_DIO_PAGES 64 /* default serialized dio pages */
> > > +
> > > /* vector size for gang look-up from extent cache that consists of radix tree */
> > > #define EXT_TREE_VEC_SIZE 64
> > >
> > > @@ -784,6 +786,7 @@ struct f2fs_sb_info {
> > > unsigned int total_valid_inode_count; /* valid inode count */
> > > int active_logs; /* # of active logs */
> > > int dir_level; /* directory level */
> > > + int serialized_dio_pages; /* serialized direct IO pages */
> > >
> > > block_t user_block_count; /* # of user blocks */
> > > block_t total_valid_block_count; /* # of valid blocks */
> > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > > index 75704d9..ebe9bd4 100644
> > > --- a/fs/f2fs/super.c
> > > +++ b/fs/f2fs/super.c
> > > @@ -218,6 +218,7 @@ F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ram_thresh, ram_thresh);
> > > F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ra_nid_pages, ra_nid_pages);
> > > F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, max_victim_search, max_victim_search);
> > > F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, dir_level, dir_level);
> > > +F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, serialized_dio_pages, serialized_dio_pages);
> > > F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, cp_interval, cp_interval);
> > >
> > > #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
> > > @@ -234,6 +235,7 @@ static struct attribute *f2fs_attrs[] = {
> > > ATTR_LIST(min_fsync_blocks),
> > > ATTR_LIST(max_victim_search),
> > > ATTR_LIST(dir_level),
> > > + ATTR_LIST(serialized_dio_pages),
> > > ATTR_LIST(ram_thresh),
> > > ATTR_LIST(ra_nid_pages),
> > > ATTR_LIST(cp_interval),
> > > @@ -1125,6 +1127,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
> > > atomic_set(&sbi->nr_pages[i], 0);
> > >
> > > sbi->dir_level = DEF_DIR_LEVEL;
> > > + sbi->serialized_dio_pages = DEF_SERIALIZED_DIO_PAGES;
> > > sbi->cp_interval = DEF_CP_INTERVAL;
> > > clear_sbi_flag(sbi, SBI_NEED_FSCK);
> > >
> > > --
> > > 2.6.3
> > >
>
>
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