* Re: Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better performance
@ 2013-09-11 2:36 Chao Yu
2013-09-11 13:14 ` Kim Jaegeuk
0 siblings, 1 reply; 4+ messages in thread
From: Chao Yu @ 2013-09-11 2:36 UTC (permalink / raw)
To: ???
Cc: 谭姝, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Hi Kim,
I did some tests as you mention of using random instead of spin_lock.
The test model is as following:
eight threads race to grab one of eight locks for one thousand times,
and I used four methods to generate lock num:
1.atomic_add_return(1, &sbi->next_lock_num) % NR_GLOBAL_LOCKS;
2.spin_lock(); next_lock_num++ % NR_GLOBAL_LOCKS; spin_unlock();
3.ktime_get().tv64 % NR_GLOBAL_LOCKS;
4.get_random_bytes(&next_lock, sizeof(unsigned int));
the result indicate that:
max count of collide continuously: 4 > 3 > 2 = 1
max-min count of lock is grabbed: 4 > 3 > 2 = 1
elapsed time of generating: 3 > 2 > 4 > 1
So I think it's better to use atomic_add_return in round-robin method to
cost less time and reduce collide.
What's your opinion?
thanks
------- Original Message -------
Sender : ???<jaegeuk.kim@samsung.com> S5(??)/??/?????????(???)/????
Date : 九月 10, 2013 09:52 (GMT+09:00)
Title : Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better performance
Hi,
At first, thank you for the report and please follow the email writing
rules. :)
Anyway, I agree to the below issue.
One thing that I can think of is that we don't need to use the
spin_lock, since we don't care about the exact lock number, but just
need to get any not-collided number.
So, how about removing the spin_lock?
And how about using a random number?
Thanks,
2013-09-06 (?), 09:48 +0000, Chao Yu:
> Hi Kim:
>
> I think there is a performance problem: when all sbi->fs_lock is
> holded,
>
> then all other threads may get the same next_lock value from
> sbi->next_lock_num in function mutex_lock_op,
>
> and wait to get the same lock at position fs_lock[next_lock], it
> unbalance the fs_lock usage.
>
> It may lost performance when we do the multithread test.
>
>
>
> Here is the patch to fix this problem:
>
>
>
> Signed-off-by: Yu Chao
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>
> old mode 100644
>
> new mode 100755
>
> index 467d42d..983bb45
>
> --- a/fs/f2fs/f2fs.h
>
> +++ b/fs/f2fs/f2fs.h
>
> @@ -371,6 +371,7 @@ struct f2fs_sb_info {
>
> struct mutex fs_lock[NR_GLOBAL_LOCKS]; /* blocking FS
> operations */
>
> struct mutex node_write; /* locking node writes
> */
>
> struct mutex writepages; /* mutex for
> writepages() */
>
> + spinlock_t spin_lock; /* lock for
> next_lock_num */
>
> unsigned char next_lock_num; /* round-robin global
> locks */
>
> int por_doing; /* recovery is doing
> or not */
>
> int on_build_free_nids; /* build_free_nids is
> doing */
>
> @@ -533,15 +534,19 @@ static inline void mutex_unlock_all(struct
> f2fs_sb_info *sbi)
>
>
>
> static inline int mutex_lock_op(struct f2fs_sb_info *sbi)
>
> {
>
> - unsigned char next_lock = sbi->next_lock_num %
> NR_GLOBAL_LOCKS;
>
> + unsigned char next_lock;
>
> int i = 0;
>
>
>
> for (; i < NR_GLOBAL_LOCKS; i++)
>
> if (mutex_trylock(&sbi->fs_lock[i]))
>
> return i;
>
>
>
> - mutex_lock(&sbi->fs_lock[next_lock]);
>
> + spin_lock(&sbi->spin_lock);
>
> + next_lock = sbi->next_lock_num % NR_GLOBAL_LOCKS;
>
> sbi->next_lock_num++;
>
> + spin_unlock(&sbi->spin_lock);
>
> +
>
> + mutex_lock(&sbi->fs_lock[next_lock]);
>
> return next_lock;
>
> }
>
>
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>
> old mode 100644
>
> new mode 100755
>
> index 75c7dc3..4f27596
>
> --- a/fs/f2fs/super.c
>
> +++ b/fs/f2fs/super.c
>
> @@ -657,6 +657,7 @@ static int f2fs_fill_super(struct super_block *sb,
> void *data, int silent)
>
> mutex_init(&sbi->cp_mutex);
>
> for (i = 0; i < NR_GLOBAL_LOCKS; i++)
>
> mutex_init(&sbi->fs_lock[i]);
>
> + spin_lock_init(&sbi->spin_lock);
>
> mutex_init(&sbi->node_write);
>
> sbi->por_doing = 0;
>
> spin_lock_init(&sbi->stat_lock);
>
> (END)
>
>
>
>
>
>
--
Jaegeuk Kim
Samsung
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better performance
2013-09-11 2:36 Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better performance Chao Yu
@ 2013-09-11 13:14 ` Kim Jaegeuk
2013-09-12 2:02 ` 俞超
0 siblings, 1 reply; 4+ messages in thread
From: Kim Jaegeuk @ 2013-09-11 13:14 UTC (permalink / raw)
To: chao2.yu
Cc: ???, 谭姝, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Hi,
2013/9/11 Chao Yu <chao2.yu@samsung.com>
>
> Hi Kim,
>
> I did some tests as you mention of using random instead of spin_lock.
> The test model is as following:
> eight threads race to grab one of eight locks for one thousand times,
> and I used four methods to generate lock num:
>
> 1.atomic_add_return(1, &sbi->next_lock_num) % NR_GLOBAL_LOCKS;
> 2.spin_lock(); next_lock_num++ % NR_GLOBAL_LOCKS; spin_unlock();
> 3.ktime_get().tv64 % NR_GLOBAL_LOCKS;
> 4.get_random_bytes(&next_lock, sizeof(unsigned int));
>
> the result indicate that:
> max count of collide continuously: 4 > 3 > 2 = 1
> max-min count of lock is grabbed: 4 > 3 > 2 = 1
> elapsed time of generating: 3 > 2 > 4 > 1
>
> So I think it's better to use atomic_add_return in round-robin method to
> cost less time and reduce collide.
> What's your opinion?
Could you test with sbi->next_lock_num++ only instead of using
atomic_add_return?
IMO, this is just an integer value and still I don't think this value should
be covered by any kind of locks.
Thanks,
>
> thanks
>
> ------- Original Message -------
> Sender : ???<jaegeuk.kim@samsung.com> S5(??)/??/?????????(???)/????
> Date : 九月 10, 2013 09:52 (GMT+09:00)
> Title : Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better performance
>
> Hi,
>
> At first, thank you for the report and please follow the email writing
> rules. :)
>
> Anyway, I agree to the below issue.
> One thing that I can think of is that we don't need to use the
> spin_lock, since we don't care about the exact lock number, but just
> need to get any not-collided number.
>
> So, how about removing the spin_lock?
> And how about using a random number?
> Thanks,
>
> 2013-09-06 (?), 09:48 +0000, Chao Yu:
> > Hi Kim:
> >
> > I think there is a performance problem: when all sbi->fs_lock is
> > holded,
> >
> > then all other threads may get the same next_lock value from
> > sbi->next_lock_num in function mutex_lock_op,
> >
> > and wait to get the same lock at position fs_lock[next_lock], it
> > unbalance the fs_lock usage.
> >
> > It may lost performance when we do the multithread test.
> >
> >
> >
> > Here is the patch to fix this problem:
> >
> >
> >
> > Signed-off-by: Yu Chao
> >
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >
> > old mode 100644
> >
> > new mode 100755
> >
> > index 467d42d..983bb45
> >
> > --- a/fs/f2fs/f2fs.h
> >
> > +++ b/fs/f2fs/f2fs.h
> >
> > @@ -371,6 +371,7 @@ struct f2fs_sb_info {
> >
> > struct mutex fs_lock[NR_GLOBAL_LOCKS]; /* blocking FS
> > operations */
> >
> > struct mutex node_write; /* locking node writes
> > */
> >
> > struct mutex writepages; /* mutex for
> > writepages() */
> >
> > + spinlock_t spin_lock; /* lock for
> > next_lock_num */
> >
> > unsigned char next_lock_num; /* round-robin global
> > locks */
> >
> > int por_doing; /* recovery is doing
> > or not */
> >
> > int on_build_free_nids; /* build_free_nids is
> > doing */
> >
> > @@ -533,15 +534,19 @@ static inline void mutex_unlock_all(struct
> > f2fs_sb_info *sbi)
> >
> >
> >
> > static inline int mutex_lock_op(struct f2fs_sb_info *sbi)
> >
> > {
> >
> > - unsigned char next_lock = sbi->next_lock_num %
> > NR_GLOBAL_LOCKS;
> >
> > + unsigned char next_lock;
> >
> > int i = 0;
> >
> >
> >
> > for (; i < NR_GLOBAL_LOCKS; i++)
> >
> > if (mutex_trylock(&sbi->fs_lock[i]))
> >
> > return i;
> >
> >
> >
> > - mutex_lock(&sbi->fs_lock[next_lock]);
> >
> > + spin_lock(&sbi->spin_lock);
> >
> > + next_lock = sbi->next_lock_num % NR_GLOBAL_LOCKS;
> >
> > sbi->next_lock_num++;
> >
> > + spin_unlock(&sbi->spin_lock);
> >
> > +
> >
> > + mutex_lock(&sbi->fs_lock[next_lock]);
> >
> > return next_lock;
> >
> > }
> >
> >
> >
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >
> > old mode 100644
> >
> > new mode 100755
> >
> > index 75c7dc3..4f27596
> >
> > --- a/fs/f2fs/super.c
> >
> > +++ b/fs/f2fs/super.c
> >
> > @@ -657,6 +657,7 @@ static int f2fs_fill_super(struct super_block *sb,
> > void *data, int silent)
> >
> > mutex_init(&sbi->cp_mutex);
> >
> > for (i = 0; i < NR_GLOBAL_LOCKS; i++)
> >
> > mutex_init(&sbi->fs_lock[i]);
> >
> > + spin_lock_init(&sbi->spin_lock);
> >
> > mutex_init(&sbi->node_write);
> >
> > sbi->por_doing = 0;
> >
> > spin_lock_init(&sbi->stat_lock);
> >
> > (END)
> >
> >
> >
> >
> >
> >
>
> --
> Jaegeuk Kim
> Samsung
--
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better performance
2013-09-11 13:14 ` Kim Jaegeuk
@ 2013-09-12 2:02 ` 俞超
0 siblings, 0 replies; 4+ messages in thread
From: 俞超 @ 2013-09-12 2:02 UTC (permalink / raw)
To: 'Kim Jaegeuk'
Cc: '???', '谭姝', linux-fsdevel,
linux-kernel, linux-f2fs-devel
Hi Kim
> -----Original Message-----
> From: Kim Jaegeuk [mailto:jaegeuk.kim@gmail.com]
> Sent: Wednesday, September 11, 2013 9:15 PM
> To: chao2.yu@samsung.com
> Cc: ???; 谭姝; linux-fsdevel@vger.kernel.org;
linux-kernel@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Subject: Re: Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better
performance
>
> Hi,
>
> 2013/9/11 Chao Yu <chao2.yu@samsung.com>
> >
> > Hi Kim,
> >
> > I did some tests as you mention of using random instead of spin_lock.
> > The test model is as following:
> > eight threads race to grab one of eight locks for one thousand times,
> > and I used four methods to generate lock num:
> >
> > 1.atomic_add_return(1, &sbi->next_lock_num) % NR_GLOBAL_LOCKS;
> > 2.spin_lock(); next_lock_num++ % NR_GLOBAL_LOCKS; spin_unlock();
> > 3.ktime_get().tv64 % NR_GLOBAL_LOCKS;
> > 4.get_random_bytes(&next_lock, sizeof(unsigned int));
> >
> > the result indicate that:
> > max count of collide continuously: 4 > 3 > 2 = 1 max-min count of lock
> > is grabbed: 4 > 3 > 2 = 1 elapsed time of generating: 3 > 2 > 4 > 1
> >
> > So I think it's better to use atomic_add_return in round-robin method
> > to cost less time and reduce collide.
> > What's your opinion?
>
> Could you test with sbi->next_lock_num++ only instead of using
> atomic_add_return?
> IMO, this is just an integer value and still I don't think this value
should be
> covered by any kind of locks.
> Thanks,
Thanks for the advice, I have tested sbi->next_lock_num++.
The time cost of it is a little bit lower than the atomic one's.
for running 8 thread for 1000000 times test.
the performance of it's balance and collide play quit well than I expected.
Can we modify this patch as following?
root@virtaulmachine:/home/yuchao/git/linux-next/fs/f2fs# git diff --stat
fs/f2fs/f2fs.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
root@virtaulmachine:/home/yuchao/git/linux-next/fs/f2fs# git diff
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 608f0df..7fd99d8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -544,15 +544,15 @@ static inline void mutex_unlock_all(struct
f2fs_sb_info *sbi)
static inline int mutex_lock_op(struct f2fs_sb_info *sbi)
{
- unsigned char next_lock = sbi->next_lock_num % NR_GLOBAL_LOCKS;
+ unsigned char next_lock;
int i = 0;
for (; i < NR_GLOBAL_LOCKS; i++)
if (mutex_trylock(&sbi->fs_lock[i]))
return i;
+ next_lock = sbi->next_lock_num++ % NR_GLOBAL_LOCKS;
mutex_lock(&sbi->fs_lock[next_lock]);
- sbi->next_lock_num++;
return next_lock;
}
>
> >
> > thanks
> >
> > ------- Original Message -------
> > Sender : ???<jaegeuk.kim@samsung.com> S5(??)/??/?????????(???)/????
> > Date : 九月 10, 2013 09:52 (GMT+09:00)
> > Title : Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better
> > performance
> >
> > Hi,
> >
> > At first, thank you for the report and please follow the email writing
> > rules. :)
> >
> > Anyway, I agree to the below issue.
> > One thing that I can think of is that we don't need to use the
> > spin_lock, since we don't care about the exact lock number, but just
> > need to get any not-collided number.
> >
> > So, how about removing the spin_lock?
> > And how about using a random number?
> > Thanks,
> >
> > 2013-09-06 (?), 09:48 +0000, Chao Yu:
> > > Hi Kim:
> > >
> > > I think there is a performance problem: when all sbi->fs_lock
> > > is holded,
> > >
> > > then all other threads may get the same next_lock value from
> > > sbi->next_lock_num in function mutex_lock_op,
> > >
> > > and wait to get the same lock at position fs_lock[next_lock], it
> > > unbalance the fs_lock usage.
> > >
> > > It may lost performance when we do the multithread test.
> > >
> > >
> > >
> > > Here is the patch to fix this problem:
> > >
> > >
> > >
> > > Signed-off-by: Yu Chao
> > >
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > >
> > > old mode 100644
> > >
> > > new mode 100755
> > >
> > > index 467d42d..983bb45
> > >
> > > --- a/fs/f2fs/f2fs.h
> > >
> > > +++ b/fs/f2fs/f2fs.h
> > >
> > > @@ -371,6 +371,7 @@ struct f2fs_sb_info {
> > >
> > > struct mutex fs_lock[NR_GLOBAL_LOCKS]; /* blocking FS
> > > operations */
> > >
> > > struct mutex node_write; /* locking node
> writes
> > > */
> > >
> > > struct mutex writepages; /* mutex for
> > > writepages() */
> > >
> > > + spinlock_t spin_lock; /* lock for
> > > next_lock_num */
> > >
> > > unsigned char next_lock_num; /* round-robin
> global
> > > locks */
> > >
> > > int por_doing; /* recovery is
> doing
> > > or not */
> > >
> > > int on_build_free_nids; /* build_free_nids is
> > > doing */
> > >
> > > @@ -533,15 +534,19 @@ static inline void mutex_unlock_all(struct
> > > f2fs_sb_info *sbi)
> > >
> > >
> > >
> > > static inline int mutex_lock_op(struct f2fs_sb_info *sbi)
> > >
> > > {
> > >
> > > - unsigned char next_lock = sbi->next_lock_num %
> > > NR_GLOBAL_LOCKS;
> > >
> > > + unsigned char next_lock;
> > >
> > > int i = 0;
> > >
> > >
> > >
> > > for (; i < NR_GLOBAL_LOCKS; i++)
> > >
> > > if (mutex_trylock(&sbi->fs_lock[i]))
> > >
> > > return i;
> > >
> > >
> > >
> > > - mutex_lock(&sbi->fs_lock[next_lock]);
> > >
> > > + spin_lock(&sbi->spin_lock);
> > >
> > > + next_lock = sbi->next_lock_num % NR_GLOBAL_LOCKS;
> > >
> > > sbi->next_lock_num++;
> > >
> > > + spin_unlock(&sbi->spin_lock);
> > >
> > > +
> > >
> > > + mutex_lock(&sbi->fs_lock[next_lock]);
> > >
> > > return next_lock;
> > >
> > > }
> > >
> > >
> > >
> > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > >
> > > old mode 100644
> > >
> > > new mode 100755
> > >
> > > index 75c7dc3..4f27596
> > >
> > > --- a/fs/f2fs/super.c
> > >
> > > +++ b/fs/f2fs/super.c
> > >
> > > @@ -657,6 +657,7 @@ static int f2fs_fill_super(struct super_block
> > > *sb, void *data, int silent)
> > >
> > > mutex_init(&sbi->cp_mutex);
> > >
> > > for (i = 0; i < NR_GLOBAL_LOCKS; i++)
> > >
> > > mutex_init(&sbi->fs_lock[i]);
> > >
> > > + spin_lock_init(&sbi->spin_lock);
> > >
> > > mutex_init(&sbi->node_write);
> > >
> > > sbi->por_doing = 0;
> > >
> > > spin_lock_init(&sbi->stat_lock);
> > >
> > > (END)
> > >
> > >
> > >
> > >
> > >
> > >
> >
> > --
> > Jaegeuk Kim
> > Samsung
^ permalink raw reply related [flat|nested] 4+ messages in thread
[parent not found: <04.C0.13361.61DDA225@epcpsbge5.samsung.com>]
* Re: Re: [f2fs-dev] [PATCH] f2fs: optimize fs_lock for better performance
[not found] <04.C0.13361.61DDA225@epcpsbge5.samsung.com>
@ 2013-09-10 0:59 ` Jaegeuk Kim
0 siblings, 0 replies; 4+ messages in thread
From: Jaegeuk Kim @ 2013-09-10 0:59 UTC (permalink / raw)
To: chao2.yu
Cc: Russ Knize, linux-fsdevel@vger.kernel.org, 谭姝,
linux-kernel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Hi,
2013-09-07 (토), 08:00 +0000, Chao Yu:
> Hi Knize,
>
> Thanks for your reply, I think it's actually meaningless that it's
> being named after "spin_lock",
> it's better to rename this spinlock to "round_robin_lock".
>
> This patch can only resolve the issue of unbalanced fs_lock usage,
> it can not fix the deadlock issue.
> can we fix deadlock issue through this method:
>
> - vfs_create()
> - f2fs_create() - takes an fs_lock and save current thread info into
> thread_info[NR_GLOBAL_LOCKS]
> - f2fs_add_link()
> - __f2fs_add_link()
> - init_inode_metadata()
> - f2fs_init_security()
> - security_inode_init_security()
> - f2fs_initxattrs()
> - f2fs_setxattr() - get fs_lock only if there is no current
> thread info in thread_info
>
> So it keeps one thread can only hold one fs_lock to avoid deadlock.
> Can we use this solution?
It could be.
But, I think we can avoid to grab the fs_lock at the f2fs_initxattrs()
level, since this case only happens when f2fs_initxattrs() is called.
Let's think about ut in more detail.
Thanks,
>
>
>
> thanks again!
>
>
>
> ------- Original Message -------
>
> Sender : Russ Knize<Russ.Knize@motorola.com>
>
> Date : 九月 07, 2013 04:25 (GMT+09:00)
>
> Title : Re: [f2fs-dev] [PATCH] f2fs: optimize fs_lock for better
> performance
>
>
>
> I encountered this same issue recently and solved it in much the same
> way. Can we rename "spin_lock" to something more meaningful?
>
>
> This race actually exposed a potential deadlock between f2fs_create()
> and f2fs_initxattrs():
>
>
> - vfs_create()
> - f2fs_create() - takes an fs_lock
> - f2fs_add_link()
> - __f2fs_add_link()
> - init_inode_metadata()
> - f2fs_init_security()
> - security_inode_init_security()
> - f2fs_initxattrs()
> - f2fs_setxattr() - also takes an fs_lock
>
>
> If another CPU happens to have the same lock that f2fs_setxattr() was
> trying to take because of the race around next_lock_num, we can get
> into a deadlock situation if the two threads are also contending over
> another resource (like bdi).
>
>
> Another scenario is if the above happens while another thread is in
> the middle of grabbing all of the locks via mutex_lock_all().
> f2fs_create() is holding a lock that mutex_lock_all() is waiting for
> and mutex_lock_all() is holding a lock that f2fs_setxattr() is waiting
> for.
>
>
> Russ
>
>
> On Fri, Sep 6, 2013 at 4:48 AM, Chao Yu <chao2.yu@samsung.com> wrote:
> Hi Kim:
>
> I think there is a performance problem: when all
> sbi->fs_lock is holded,
>
> then all other threads may get the same next_lock value from
> sbi->next_lock_num in function mutex_lock_op,
>
> and wait to get the same lock at position fs_lock[next_lock],
> it unbalance the fs_lock usage.
>
> It may lost performance when we do the multithread test.
>
>
>
> Here is the patch to fix this problem:
>
>
>
> Signed-off-by: Yu Chao <chao2.yu@samsung.com>
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>
> old mode 100644
>
> new mode 100755
>
> index 467d42d..983bb45
>
> --- a/fs/f2fs/f2fs.h
>
> +++ b/fs/f2fs/f2fs.h
>
> @@ -371,6 +371,7 @@ struct f2fs_sb_info {
>
> struct mutex fs_lock[NR_GLOBAL_LOCKS]; /* blocking FS
> operations */
>
> struct mutex node_write; /* locking
> node writes */
>
> struct mutex writepages; /* mutex for
> writepages() */
>
> + spinlock_t spin_lock; /* lock for
> next_lock_num */
>
> unsigned char next_lock_num; /* round-robin
> global locks */
>
> int por_doing; /* recovery is
> doing or not */
>
> int on_build_free_nids; /*
> build_free_nids is doing */
>
> @@ -533,15 +534,19 @@ static inline void
> mutex_unlock_all(struct f2fs_sb_info *sbi)
>
>
>
> static inline int mutex_lock_op(struct f2fs_sb_info *sbi)
>
> {
>
> - unsigned char next_lock = sbi->next_lock_num %
> NR_GLOBAL_LOCKS;
>
> + unsigned char next_lock;
>
> int i = 0;
>
>
>
> for (; i < NR_GLOBAL_LOCKS; i++)
>
> if (mutex_trylock(&sbi->fs_lock[i]))
>
> return i;
>
>
>
> - mutex_lock(&sbi->fs_lock[next_lock]);
>
> + spin_lock(&sbi->spin_lock);
>
> + next_lock = sbi->next_lock_num % NR_GLOBAL_LOCKS;
>
> sbi->next_lock_num++;
>
> + spin_unlock(&sbi->spin_lock);
>
> +
>
> + mutex_lock(&sbi->fs_lock[next_lock]);
>
> return next_lock;
>
> }
>
>
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>
> old mode 100644
>
> new mode 100755
>
> index 75c7dc3..4f27596
>
> --- a/fs/f2fs/super.c
>
> +++ b/fs/f2fs/super.c
>
> @@ -657,6 +657,7 @@ static int f2fs_fill_super(struct
> super_block *sb, void *data, int silent)
>
> mutex_init(&sbi->cp_mutex);
>
> for (i = 0; i < NR_GLOBAL_LOCKS; i++)
>
> mutex_init(&sbi->fs_lock[i]);
>
> + spin_lock_init(&sbi->spin_lock);
>
> mutex_init(&sbi->node_write);
>
> sbi->por_doing = 0;
>
> spin_lock_init(&sbi->stat_lock);
>
> (END)
>
>
>
>
>
>
>
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>
>
>
>
>
>
>
>
>
>
>
>
--
Jaegeuk Kim
Samsung
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-09-12 2:02 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-09-11 2:36 Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better performance Chao Yu
2013-09-11 13:14 ` Kim Jaegeuk
2013-09-12 2:02 ` 俞超
[not found] <04.C0.13361.61DDA225@epcpsbge5.samsung.com>
2013-09-10 0:59 ` Re: [f2fs-dev] [PATCH] " Jaegeuk Kim
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