Messages in this thread | | | Date | Mon, 13 Aug 2018 21:04:34 -0700 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH v3] f2fs: fix performance issue observed with multi-thread sequential read |
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On 08/14, Chao Yu wrote: > On 2018/8/14 4:11, Jaegeuk Kim wrote: > > On 08/13, Chao Yu wrote: > >> Hi Jaegeuk, > >> > >> On 2018/8/11 2:56, Jaegeuk Kim wrote: > >>> This reverts the commit - "b93f771 - f2fs: remove writepages lock" > >>> to fix the drop in sequential read throughput. > >>> > >>> Test: ./tiotest -t 32 -d /data/tio_tmp -f 32 -b 524288 -k 1 -k 3 -L > >>> device: UFS > >>> > >>> Before - > >>> read throughput: 185 MB/s > >>> total read requests: 85177 (of these ~80000 are 4KB size requests). > >>> total write requests: 2546 (of these ~2208 requests are written in 512KB). > >>> > >>> After - > >>> read throughput: 758 MB/s > >>> total read requests: 2417 (of these ~2042 are 512KB reads). > >>> total write requests: 2701 (of these ~2034 requests are written in 512KB). > >> > >> IMO, it only impact sequential read performance in a large file which may be > >> fragmented during multi-thread writing. > >> > >> In android environment, mostly, the large file should be cold type, such as apk, > >> mp3, rmvb, jpeg..., so I think we only need to serialize writepages() for cold > >> data area writer. > >> > >> So how about adding a mount option to serialize writepage() for different type > >> of log, e.g. in android, using serialize=4; by default, using serialize=7 > >> HOT_DATA 1 > >> WARM_DATA 2 > >> COLD_DATA 4 > > > > Well, I don't think we need to give too many mount options for this fragmented > > case. How about doing this for the large files only like this? > > Thread A write 512 pages Thread B write 8 pages > > - writepages() > - mutex_lock(&sbi->writepages); > - writepage(); > ... > - writepages() > - writepage() > .... > - writepage(); > ... > - mutex_unlock(&sbi->writepages); > > Above case will also cause fragmentation since we didn't serialize all > concurrent IO with the lock. > > Do we need to consider such case?
We can simply allow 512 and 8 in the same segment, which would not a big deal, when considering starvation of Thread B.
> > Thanks, > > > > >>From 4fea0b6e4da8512a72dd52afc7a51beb35966ad9 Mon Sep 17 00:00:00 2001 > > From: Jaegeuk Kim <jaegeuk@kernel.org> > > Date: Thu, 9 Aug 2018 17:53:34 -0700 > > Subject: [PATCH] f2fs: fix performance issue observed with multi-thread > > sequential read > > > > This reverts the commit - "b93f771 - f2fs: remove writepages lock" > > to fix the drop in sequential read throughput. > > > > Test: ./tiotest -t 32 -d /data/tio_tmp -f 32 -b 524288 -k 1 -k 3 -L > > device: UFS > > > > Before - > > read throughput: 185 MB/s > > total read requests: 85177 (of these ~80000 are 4KB size requests). > > total write requests: 2546 (of these ~2208 requests are written in 512KB). > > > > After - > > read throughput: 758 MB/s > > total read requests: 2417 (of these ~2042 are 512KB reads). > > total write requests: 2701 (of these ~2034 requests are written in 512KB). > > > > Signed-off-by: Sahitya Tummala <stummala@codeaurora.org> > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > --- > > Documentation/ABI/testing/sysfs-fs-f2fs | 8 ++++++++ > > fs/f2fs/data.c | 10 ++++++++++ > > fs/f2fs/f2fs.h | 2 ++ > > fs/f2fs/segment.c | 1 + > > fs/f2fs/super.c | 1 + > > fs/f2fs/sysfs.c | 2 ++ > > 6 files changed, 24 insertions(+) > > > > diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs > > index 9b0123388f18..94a24aedcdb2 100644 > > --- a/Documentation/ABI/testing/sysfs-fs-f2fs > > +++ b/Documentation/ABI/testing/sysfs-fs-f2fs > > @@ -51,6 +51,14 @@ Description: > > Controls the dirty page count condition for the in-place-update > > policies. > > > > +What: /sys/fs/f2fs/<disk>/min_seq_blocks > > +Date: August 2018 > > +Contact: "Jaegeuk Kim" <jaegeuk@kernel.org> > > +Description: > > + Controls the dirty page count condition for batched sequential > > + writes in ->writepages. > > + > > + > > What: /sys/fs/f2fs/<disk>/min_hot_blocks > > Date: March 2017 > > Contact: "Jaegeuk Kim" <jaegeuk@kernel.org> > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > index 45f043ee48bd..f09231b1cc74 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -2132,6 +2132,7 @@ static int __f2fs_write_data_pages(struct address_space *mapping, > > struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > > struct blk_plug plug; > > int ret; > > + bool locked = false; > > > > /* deal with chardevs and other special file */ > > if (!mapping->a_ops->writepage) > > @@ -2162,10 +2163,19 @@ static int __f2fs_write_data_pages(struct address_space *mapping, > > else if (atomic_read(&sbi->wb_sync_req[DATA])) > > goto skip_write; > > > > + if (!S_ISDIR(inode->i_mode) && > > + get_dirty_pages(inode) <= SM_I(sbi)->min_seq_blocks) { > > + mutex_lock(&sbi->writepages); > > + locked = true; > > + } > > + > > blk_start_plug(&plug); > > ret = f2fs_write_cache_pages(mapping, wbc, io_type); > > blk_finish_plug(&plug); > > > > + if (locked) > > + mutex_unlock(&sbi->writepages); > > + > > if (wbc->sync_mode == WB_SYNC_ALL) > > atomic_dec(&sbi->wb_sync_req[DATA]); > > /* > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index 375aa9f30cfa..098bdedc28bf 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -913,6 +913,7 @@ struct f2fs_sm_info { > > unsigned int ipu_policy; /* in-place-update policy */ > > unsigned int min_ipu_util; /* in-place-update threshold */ > > unsigned int min_fsync_blocks; /* threshold for fsync */ > > + unsigned int min_seq_blocks; /* threshold for sequential blocks */ > > unsigned int min_hot_blocks; /* threshold for hot block allocation */ > > unsigned int min_ssr_sections; /* threshold to trigger SSR allocation */ > > > > @@ -1133,6 +1134,7 @@ struct f2fs_sb_info { > > struct rw_semaphore sb_lock; /* lock for raw super block */ > > int valid_super_block; /* valid super block no */ > > unsigned long s_flag; /* flags for sbi */ > > + struct mutex writepages; /* mutex for writepages() */ > > > > #ifdef CONFIG_BLK_DEV_ZONED > > unsigned int blocks_per_blkz; /* F2FS blocks per zone */ > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > index 63fc647f9ac2..ffea2d1303bd 100644 > > --- a/fs/f2fs/segment.c > > +++ b/fs/f2fs/segment.c > > @@ -4131,6 +4131,7 @@ int f2fs_build_segment_manager(struct f2fs_sb_info *sbi) > > sm_info->ipu_policy = 1 << F2FS_IPU_FSYNC; > > sm_info->min_ipu_util = DEF_MIN_IPU_UTIL; > > sm_info->min_fsync_blocks = DEF_MIN_FSYNC_BLOCKS; > > + sm_info->min_seq_blocks = sbi->blocks_per_seg * sbi->segs_per_sec; > > sm_info->min_hot_blocks = DEF_MIN_HOT_BLOCKS; > > sm_info->min_ssr_sections = reserved_sections(sbi); > > > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > > index be41dbd7b261..53d70b64fea1 100644 > > --- a/fs/f2fs/super.c > > +++ b/fs/f2fs/super.c > > @@ -2842,6 +2842,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) > > /* init f2fs-specific super block info */ > > sbi->valid_super_block = valid_super_block; > > mutex_init(&sbi->gc_mutex); > > + mutex_init(&sbi->writepages); > > mutex_init(&sbi->cp_mutex); > > init_rwsem(&sbi->node_write); > > init_rwsem(&sbi->node_change); > > diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c > > index cd2e030e47b8..81c0e5337443 100644 > > --- a/fs/f2fs/sysfs.c > > +++ b/fs/f2fs/sysfs.c > > @@ -397,6 +397,7 @@ F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, batched_trim_sections, trim_sections); > > F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, ipu_policy, ipu_policy); > > F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_ipu_util, min_ipu_util); > > F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_fsync_blocks, min_fsync_blocks); > > +F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_seq_blocks, min_seq_blocks); > > F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_hot_blocks, min_hot_blocks); > > F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_ssr_sections, min_ssr_sections); > > F2FS_RW_ATTR(NM_INFO, f2fs_nm_info, ram_thresh, ram_thresh); > > @@ -449,6 +450,7 @@ static struct attribute *f2fs_attrs[] = { > > ATTR_LIST(ipu_policy), > > ATTR_LIST(min_ipu_util), > > ATTR_LIST(min_fsync_blocks), > > + ATTR_LIST(min_seq_blocks), > > ATTR_LIST(min_hot_blocks), > > ATTR_LIST(min_ssr_sections), > > ATTR_LIST(max_victim_search), > >
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