On Thu, Jul 31, 2014 at 01:31:46PM +0800, Chao Yu wrote: > Hi Changman, > > > -----Original Message----- > > From: Changman Lee [mailto:cm224.lee@xxxxxxxxxxx] > > Sent: Thursday, July 31, 2014 10:07 AM > > To: Chao Yu > > Cc: 'Jaegeuk Kim'; linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > Subject: Re: [f2fs-dev] [PATCH] f2fs: reduce competition among node page writes > > > > Hi Chao, > > > > On Wed, Jul 30, 2014 at 09:07:49PM +0800, Chao Yu wrote: > > > Hi Jaegeuk Changman, > > > > > > > -----Original Message----- > > > > From: Chao Yu [mailto:chao2.yu@xxxxxxxxxxx] > > > > Sent: Thursday, July 03, 2014 6:59 PM > > > > To: Jaegeuk Kim; Changman Lee > > > > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > > > Subject: [f2fs-dev] [PATCH] f2fs: reduce competition among node page writes > > > > > > > > We do not need to block on ->node_write among different node page writers e.g. > > > > fsync/flush, unless we have a node page writer from write_checkpoint. > > > > So it's better use rw_semaphore instead of mutex type for ->node_write to > > > > promote performance. > > > > > > If you could have time to help explaining the problem of this patch, I will be > > > appreciated for that. > > > > I have no clue. Except checkpoint, I don't know why need to block to > > write node page. > > Do you have any problem when you test with this patch? > > I don't have. > I send this patch about one month ago, but got no respond. > So I want to ask if any problem in this patch or forget to look at this patch? > > To Jaegeuk: > Any idea about this patch? Oh, I forgot to send an email for this. At that time, when I looked at a glance, I thought that it was not clear why this should be merged. But, when I contemplate again, it seems that several fsync threads could produce multiple node writers, resulting in some mutex contention. Just for sure, can you verify that? Nevertheless, I think there would be no problem to merge this patch now. Merged. > > > > > > > > > Another question is what is ->writepages in sbi used for? I'm not quite clear. > > > > > > > I remember it is for writing data pages per thread as much as possible. > > When multi-threads write some files simultaneously, multi-threads contended with > > each other to allocate a block. So block allocation was interleaved > > across threads. It makes fragmentation of file. Good. :) > > Thank you for the explanation! :) > I think what you say is reasonable. > > Previously I tested without this lock, although I found that the blocks written > _almost_ were continuous in each '->writepages()'. Still I think we can gain more > from readahead continuous block when using this lock, rather than remove it for > promoting concurrent of writers. > > Thanks, > Yu > > > > > Thanks, > > > > > Thanks, > > > > > > > > > > > Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx> > > > > --- > > > > fs/f2fs/checkpoint.c | 6 +++--- > > > > fs/f2fs/f2fs.h | 2 +- > > > > fs/f2fs/node.c | 4 ++-- > > > > fs/f2fs/super.c | 2 +- > > > > 4 files changed, 7 insertions(+), 7 deletions(-) > > > > > > > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > > > > index 0b4710c..eec406b 100644 > > > > --- a/fs/f2fs/checkpoint.c > > > > +++ b/fs/f2fs/checkpoint.c > > > > @@ -714,10 +714,10 @@ retry_flush_dents: > > > > * until finishing nat/sit flush. > > > > */ > > > > retry_flush_nodes: > > > > - mutex_lock(&sbi->node_write); > > > > + down_write(&sbi->node_write); > > > > > > > > if (get_pages(sbi, F2FS_DIRTY_NODES)) { > > > > - mutex_unlock(&sbi->node_write); > > > > + up_write(&sbi->node_write); > > > > sync_node_pages(sbi, 0, &wbc); > > > > goto retry_flush_nodes; > > > > } > > > > @@ -726,7 +726,7 @@ retry_flush_nodes: > > > > > > > > static void unblock_operations(struct f2fs_sb_info *sbi) > > > > { > > > > - mutex_unlock(&sbi->node_write); > > > > + up_write(&sbi->node_write); > > > > f2fs_unlock_all(sbi); > > > > } > > > > > > > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > > > index ae3b4ac..ca30b5a 100644 > > > > --- a/fs/f2fs/f2fs.h > > > > +++ b/fs/f2fs/f2fs.h > > > > @@ -444,7 +444,7 @@ struct f2fs_sb_info { > > > > struct inode *meta_inode; /* cache meta blocks */ > > > > struct mutex cp_mutex; /* checkpoint procedure lock */ > > > > struct rw_semaphore cp_rwsem; /* blocking FS operations */ > > > > - struct mutex node_write; /* locking node writes */ > > > > + struct rw_semaphore node_write; /* locking node writes */ > > > > struct mutex writepages; /* mutex for writepages() */ > > > > bool por_doing; /* recovery is doing or not */ > > > > wait_queue_head_t cp_wait; > > > > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > > > > index a90f51d..7b5b5de 100644 > > > > --- a/fs/f2fs/node.c > > > > +++ b/fs/f2fs/node.c > > > > @@ -1231,12 +1231,12 @@ static int f2fs_write_node_page(struct page *page, > > > > if (wbc->for_reclaim) > > > > goto redirty_out; > > > > > > > > - mutex_lock(&sbi->node_write); > > > > + down_read(&sbi->node_write); > > > > set_page_writeback(page); > > > > write_node_page(sbi, page, &fio, nid, ni.blk_addr, &new_addr); > > > > set_node_addr(sbi, &ni, new_addr, is_fsync_dnode(page)); > > > > dec_page_count(sbi, F2FS_DIRTY_NODES); > > > > - mutex_unlock(&sbi->node_write); > > > > + up_read(&sbi->node_write); > > > > unlock_page(page); > > > > return 0; > > > > > > > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > > > > index 8f96d93..bed9413 100644 > > > > --- a/fs/f2fs/super.c > > > > +++ b/fs/f2fs/super.c > > > > @@ -947,7 +947,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) > > > > mutex_init(&sbi->gc_mutex); > > > > mutex_init(&sbi->writepages); > > > > mutex_init(&sbi->cp_mutex); > > > > - mutex_init(&sbi->node_write); > > > > + init_rwsem(&sbi->node_write); > > > > sbi->por_doing = false; > > > > spin_lock_init(&sbi->stat_lock); > > > > > > > > -- > > > > 1.7.9.5 > > > > > > > > > > > > > > > > ------------------------------------------------------------------------------ > > > > Open source business process management suite built on Java and Eclipse > > > > Turn processes into business applications with Bonita BPM Community Edition > > > > Quickly connect people, data, and systems into organized workflows > > > > Winner of BOSSIE, CODIE, OW2 and Gartner awards > > > > http://p.sf.net/sfu/Bonitasoft > > > > _______________________________________________ > > > > Linux-f2fs-devel mailing list > > > > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
