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Date: Mon, 25 Jan 2016 11:17:51 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao2.yu@...sung.com>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: avoid multiple node page writes due
to inline_data
Hi Chao,
On Mon, Jan 25, 2016 at 05:42:40PM +0800, Chao Yu wrote:
> Hi Jaegeuk,
>
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk@...nel.org]
> > Sent: Sunday, January 24, 2016 4:16 AM
> > To: linux-kernel@...r.kernel.org; linux-fsdevel@...r.kernel.org;
> > linux-f2fs-devel@...ts.sourceforge.net
> > Cc: Jaegeuk Kim
> > Subject: [f2fs-dev] [PATCH 1/2] f2fs: avoid multiple node page writes due to inline_data
> >
> > The sceanrio is:
> > 1. create fully node blocks
> > 2. flush node blocks
> > 3. write inline_data for all the node blocks again
> > 4. flush node blocks redundantly
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> > ---
> > fs/f2fs/data.c | 14 +++++++++++---
> > 1 file changed, 11 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index 8d0d9ec..011456e 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -1622,14 +1622,22 @@ static int f2fs_write_end(struct file *file,
> >
> > trace_f2fs_write_end(inode, pos, len, copied);
> >
> > - set_page_dirty(page);
> > -
> > if (pos + copied > i_size_read(inode)) {
> > i_size_write(inode, pos + copied);
> > mark_inode_dirty(inode);
> > - update_inode_page(inode);
> > }
> >
> > + if (f2fs_has_inline_data(inode) &&
> > + is_inode_flag_set(F2FS_I(inode), FI_DATA_EXIST)) {
> > + int err = f2fs_write_inline_data(inode, page);
>
> Oh, I'm sure this can fix that issue, but IMO:
> a) this implementation has side-effect, it triggers inline data copying
> between data page and node page whenever user write inline datas, so if
> user updates inline data frequently, write-through approach would cause
> memory copy overhead.
Agreed.
> b) inline storm should be a rare case, as we didn't get any report about
> problem for long time until Dave's, and write_end is a hot path, I think
> it's better to be cautious to change our inline data cache policy for
> fixing a rare issue in hot path.
>
> What about delaying the merge operation? like:
> 1) as I proposed before, merging inline page into inode page when
> detecting free_sections <= (node_secs + 2 * dent_secs + inline_secs).
> 2) merge inline page into inode page before writeback inode page in
> sync_node_pages.
Okay, I'm thinking more general way where we can get rid of every inlien_data
write when we flush node pages.
I've been testing this patch.
>From ebddf607c64da691fef08cf68a8ecadafd5d896b Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk@...nel.org>
Date: Mon, 25 Jan 2016 05:57:05 -0800
Subject: [PATCH] f2fs: avoid multiple node page writes due to inline_data
The sceanrio is:
1. create fully node blocks
2. flush node blocks
3. write inline_data for all the node blocks again
4. flush node blocks redundantly
So, this patch tries to flush inline_data when flushing node blocks.
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
fs/f2fs/data.c | 1 +
fs/f2fs/inline.c | 2 ++
fs/f2fs/node.c | 35 +++++++++++++++++++++++++++++++++++
fs/f2fs/node.h | 15 +++++++++++++++
4 files changed, 53 insertions(+)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 6925c10..9043ecf 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1464,6 +1464,7 @@ restart:
if (pos + len <= MAX_INLINE_DATA) {
read_inline_data(page, ipage);
set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
+ set_inline_node(ipage);
sync_inode_page(&dn);
} else {
err = f2fs_convert_inline_page(&dn, page);
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
index 8df13e5..fc4d298 100644
--- a/fs/f2fs/inline.c
+++ b/fs/f2fs/inline.c
@@ -159,6 +159,7 @@ no_update:
/* clear inline data and flag after data writeback */
truncate_inline_inode(dn->inode_page, 0);
+ clear_inline_node(dn->inode_page);
clear_out:
stat_dec_inline_inode(dn->inode);
f2fs_clear_inline_inode(dn->inode);
@@ -233,6 +234,7 @@ int f2fs_write_inline_data(struct inode *inode, struct page *page)
set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
sync_inode_page(&dn);
+ clear_inline_node(dn.inode_page);
f2fs_put_dnode(&dn);
return 0;
}
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 23b800d..1c5023e 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1154,6 +1154,33 @@ void sync_inode_page(struct dnode_of_data *dn)
dn->node_changed = ret ? true: false;
}
+static void flush_inline_data(struct f2fs_sb_info *sbi, nid_t ino)
+{
+ struct inode *inode;
+ struct page *page;
+
+ inode = ilookup(sbi->sb, ino);
+ if (!inode)
+ return;
+
+ page = find_lock_page(inode->i_mapping, 0);
+ if (!page)
+ goto iput_out;
+
+ if (!PageDirty(page))
+ goto put_page_out;
+
+ if (!clear_page_dirty_for_io(page))
+ goto put_page_out;
+
+ if (!f2fs_write_inline_data(inode, page))
+ inode_dec_dirty_pages(inode);
+put_page_out:
+ f2fs_put_page(page, 1);
+iput_out:
+ iput(inode);
+}
+
int sync_node_pages(struct f2fs_sb_info *sbi, nid_t ino,
struct writeback_control *wbc)
{
@@ -1221,6 +1248,14 @@ continue_unlock:
goto continue_unlock;
}
+ /* flush inline_data */
+ if (!ino && is_inline_node(page)) {
+ clear_inline_node(page);
+ unlock_page(page);
+ flush_inline_data(sbi, ino_of_node(page));
+ continue;
+ }
+
if (!clear_page_dirty_for_io(page))
goto continue_unlock;
diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index 23bd992..1f4f9d4 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -379,6 +379,21 @@ static inline int is_node(struct page *page, int type)
#define is_fsync_dnode(page) is_node(page, FSYNC_BIT_SHIFT)
#define is_dent_dnode(page) is_node(page, DENT_BIT_SHIFT)
+static inline int is_inline_node(struct page *page)
+{
+ return PageChecked(page);
+}
+
+static inline void set_inline_node(struct page *page)
+{
+ SetPageChecked(page);
+}
+
+static inline void clear_inline_node(struct page *page)
+{
+ ClearPageChecked(page);
+}
+
static inline void set_cold_node(struct inode *inode, struct page *page)
{
struct f2fs_node *rn = F2FS_NODE(page);
--
2.6.3
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