Hi Yunlei,
> -----Original Message-----
> From: He YunLei [mailto:[email protected]]
> Sent: Thursday, September 17, 2015 8:40 AM
> To: Chao Yu
> Cc: 'Jaegeuk Kim'; [email protected]; [email protected]
> Subject: Re: [f2fs-dev] [PATCH 5/7] f2fs: enhance multithread dio write performance
>
> On 2015/9/16 18:15, Chao Yu wrote:
> > Hi Jaegeuk,
> >
> >> -----Original Message-----
> >> From: Jaegeuk Kim [mailto:[email protected]]
> >> Sent: Wednesday, September 16, 2015 5:21 AM
> >> To: Chao Yu
> >> Cc: [email protected]; [email protected]
> >> Subject: Re: [PATCH 5/7] f2fs: enhance multithread dio write performance
> >>
> >> Hi Chao,
> >>
> >> On Fri, Sep 11, 2015 at 02:41:53PM +0800, Chao Yu wrote:
> >>> When dio writes perform concurrently, our performace will be low because of
> >>> Thread A's allocation of multi continuous blocks will be break by Thread B,
> >>> there are two cases as below:
> >>> - In Thread B, we may change current segment to a new segment for LFS
> >>> allocation if we dio write in the beginning of the file.
> >>> - In Thread B, we may allocate blocks in the middle of Thread A's
> >>> allocation, which make blocks which allocated in Thread A being
> >>> discontinuous.
> >>>
> >>> This patch adds writepages mutex lock to make block allocation in dio write
> >>> atomic to avoid above issues.
> >>>
> >>> Test environment:
> >>> ubuntu os with linux kernel 4.2+, intel i7-3770, 16g memory,
> >>> 32g kingston sd card.
> >>>
> >>> fio --name seqw --ioengine=sync --invalidate=1 --rw=write --directory=/mnt/f2fs
> >> --filesize=256m --size=16m --bs=2m --direct=1
> >>> --numjobs=10
> >>>
> >>> before:
> >>> WRITE: io=163840KB, aggrb=3145KB/s, minb=314KB/s, maxb=411KB/s, mint=39836msec,
> >> maxt=52083msec
> >>>
> >>> patched:
> >>> WRITE: io=163840KB, aggrb=10033KB/s, minb=1003KB/s, maxb=1124KB/s, mint=14565msec,
> >> maxt=16329msec
> >>>
> >>> Signed-off-by: Chao Yu <[email protected]>
> >>> ---
> >>> fs/f2fs/data.c | 13 ++++++++++---
> >>> 1 file changed, 10 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> >>> index a737ca5..a0a5849 100644
> >>> --- a/fs/f2fs/data.c
> >>> +++ b/fs/f2fs/data.c
> >>> @@ -1536,7 +1536,9 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter
> *iter,
> >>> struct file *file = iocb->ki_filp;
> >>> struct address_space *mapping = file->f_mapping;
> >>> struct inode *inode = mapping->host;
> >>> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> >>> size_t count = iov_iter_count(iter);
> >>> + int rw = iov_iter_rw(iter);
> >>> int err;
> >>>
> >>> /* we don't need to use inline_data strictly */
> >>> @@ -1555,12 +1557,17 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter
> >> *iter,
> >>>
> >>> trace_f2fs_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
> >>>
> >>> - if (iov_iter_rw(iter) == WRITE)
> >>> + if (rw == WRITE) {
> >>> + mutex_lock(&sbi->writepages);
> >>
> >> Why do we have to share sbi->writepages?
> >
> > The root cause of this issue is that: in f2fs, we have no suitable
> > dispatcher which can do the following things as an atomic operation:
> > a) allocate position(s) in flash device for current block(s);
> > b) submit user data in allocated position(s) in block layer.
> >
> > Without the dispatcher, we will suffer performance issue in following
> > scenario:
> > Thread A Thread B Thread C
> > allocate pos+1
> > allocate pos+2
> > allocate pos+3
> > submit pos+1
> > submit pos+3
> > submit pos+2
> >
> > Our final submitting series will: pos+1, pos+3, pos+2, this makes f2fs
> > running into non-LFS mode, therefore resulting in bad performance.
> >
> > writepages mutex lock supply us with a good solution for above issue.
> > It not only make the allocating and submitting pair executing atomically,
> > but also reduce the fragmentation for one file since we submit blocks
> > belong to single inode as continuous as possible.
> >
> > So here I choose to use writepages mutex lock to fix the performance
> > issue caused by both dio write vs dio write and dio write vs buffered
> > write.
> >
> > If I'm missing something, please correct me.
> >
> >>
> >>> __allocate_data_blocks(inode, offset, count);
> >>
> >> If the problem lies on the misaligned blocks, how about calling mutex_unlock
> >> here?
> >
> > When changing to unlock here, I got regression when testing with following command:
> > fio --name seqw --ioengine=sync --invalidate=1 --rw=write --directory=/mnt/f2fs
> --filesize=256m --size=4m --bs=64k --direct=1
> > --numjobs=20
> >
> > unlock here:
> > WRITE: io=81920KB, aggrb=5802KB/s, minb=290KB/s, maxb=292KB/s, mint=14010msec,
> maxt=14119msec
> > unlock after dio finished:
> > WRITE: io=81920KB, aggrb=6088KB/s, minb=304KB/s, maxb=1081KB/s, mint=3786msec,
> maxt=13454msec
> >
> > So how about keep it in original place in this patch?
>
> 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
Could you help to test the following patch?
>From 0abff8a16bf87076ec70a7c1b8da913000e9c3b7 Mon Sep 17 00:00:00 2001
From: Chao Yu <[email protected]>
Date: Wed, 21 Oct 2015 15:12:07 +0800
Subject: [PATCH v2] f2fs: enhance multithread dio write performance
When dio writes perform concurrently, our performace will be low because of
Thread A's allocation of multi continuous blocks will be break by Thread B,
there are two cases as below:
- In Thread B, we may change current segment to a new segment for LFS
allocation if we dio write in the beginning of the file.
- In Thread B, we may allocate blocks in the middle of Thread A's
allocation, which make blocks allocated in Thread A being inconsecutive.
This patch adds writepages mutex lock to make block allocation in dio write
atomic to avoid above issues.
Test environment:
ubuntu os with linux kernel 4.4-rc4, intel i7-3770, 16g memory,
32g kingston sd card.
fio --name seqw --ioengine=sync --invalidate=1 --rw=write --directory=/mnt/f2fs --filesize=256m --size=16m --bs=2m --direct=1
--numjobs=10
before:
WRITE: io=163840KB, aggrb=5125KB/s, minb=512KB/s, maxb=776KB/s, mint=21105msec, maxt=31967msec
patched:
WRITE: io=163840KB, aggrb=10424KB/s, minb=1042KB/s, maxb=1172KB/s, mint=13975msec, maxt=15717msec
Signed-off-by: Chao Yu <[email protected]>
---
v2:
- only serialize block allocation.
- do not serialize small dio.
fs/f2fs/data.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 90a2ffe..c01d113 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1566,7 +1566,10 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
size_t count = iov_iter_count(iter);
+ int rw = iov_iter_rw(iter);
+ bool serialized = (F2FS_BYTES_TO_BLK(count) >= 64);
int err;
/* we don't need to use inline_data strictly */
@@ -1583,10 +1586,14 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
if (err)
return err;
- trace_f2fs_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
+ trace_f2fs_direct_IO_enter(inode, offset, count, rw);
- if (iov_iter_rw(iter) == WRITE) {
+ if (rw == WRITE) {
+ if (serialized)
+ mutex_lock(&sbi->writepages);
__allocate_data_blocks(inode, offset, count);
+ if (serialized)
+ mutex_unlock(&sbi->writepages);
if (unlikely(f2fs_cp_error(F2FS_I_SB(inode)))) {
err = -EIO;
goto out;
@@ -1595,10 +1602,10 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
err = blockdev_direct_IO(iocb, inode, iter, offset, get_data_block_dio);
out:
- if (err < 0 && iov_iter_rw(iter) == WRITE)
+ if (err < 0 && rw == WRITE)
f2fs_write_failed(mapping, offset + count);
- trace_f2fs_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), err);
+ trace_f2fs_direct_IO_exit(inode, offset, count, rw, err);
return err;
}
--
2.6.3
>
> >
> > Thanks,
> >>
> >> Thanks,
> >>
> >>> + }
> >>>
> >>> err = blockdev_direct_IO(iocb, inode, iter, offset, get_data_block_dio);
> >>> - if (err < 0 && iov_iter_rw(iter) == WRITE)
> >>> - f2fs_write_failed(mapping, offset + count);
> >>> + if (rw == WRITE) {
> >>> + mutex_unlock(&sbi->writepages);
> >>> + if (err)
> >>> + f2fs_write_failed(mapping, offset + count);
> >>> + }
> >>>
> >>> trace_f2fs_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), err);
> >>>
> >>> --
> >>> 2.4.2
> >
> >
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