Messages in this thread | | | Subject | Re: [f2fs-dev] [PATCH v3] f2fs: fix performance issue observed with multi-thread sequential read | From | Chao Yu <> | Date | Tue, 14 Aug 2018 14:18:09 +0800 |
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On 2018/8/14 12:04, Jaegeuk Kim wrote: > 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.
Yeah, but in reality, there would be more threads competing in same log header, so I worry that the effect of defragmenting will not so good as we expect, anyway, for benchmark, it's enough.
Thanks,
> >> >> 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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