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Date: Tue, 28 May 2019 10:22:30 -0700
From: Wengang <wen.gang.wang@...cle.com>
To: Gang He <ghe@...e.com>, mark@...heh.com, jlbec@...lplan.org,
jiangqi903@...il.com
Cc: linux-kernel@...r.kernel.org, ocfs2-devel@....oracle.com
Subject: Re: [Ocfs2-devel] [PATCH 1/2] ocfs2: add last unlock times in
locking_state
Hi Gang,
This idea sounds cool!
Some comments in lines:
On 05/23/2019 03:40 AM, Gang He wrote:
> ocfs2 file system uses locking_state file under debugfs to dump
> each ocfs2 file system's dlm lock resources, but the dlm lock
> resources in memory are becoming more and more after the files
> were touched by the user. it will become a bit difficult to analyze
> these dlm lock resource records in locking_state file by the upper
> scripts, though some files are not active for now, which were
> accessed long time ago.
> Then, I'd like to add last pr/ex unlock times in locking_state file
> for each dlm lock resource record, the the upper scripts can use
> last unlock time to filter inactive dlm lock resource record.
>
> Signed-off-by: Gang He <ghe@...e.com>
> Reviewed-by: Joseph Qi <joseph.qi@...ux.alibaba.com>
> ---
> fs/ocfs2/dlmglue.c | 21 +++++++++++++++++----
> fs/ocfs2/ocfs2.h | 1 +
> 2 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
> index af405586c5b1..dccf4136f8c1 100644
> --- a/fs/ocfs2/dlmglue.c
> +++ b/fs/ocfs2/dlmglue.c
> @@ -448,7 +448,7 @@ static void ocfs2_update_lock_stats(struct ocfs2_lock_res *res, int level,
> struct ocfs2_mask_waiter *mw, int ret)
> {
> u32 usec;
> - ktime_t kt;
> + ktime_t last, kt;
> struct ocfs2_lock_stats *stats;
>
> if (level == LKM_PRMODE)
> @@ -458,7 +458,8 @@ static void ocfs2_update_lock_stats(struct ocfs2_lock_res *res, int level,
> else
> return;
>
> - kt = ktime_sub(ktime_get(), mw->mw_lock_start);
> + last = ktime_get();
Will ktime_get_real() be better than ktime_get() here?
Per description,
ktime_get:
Useful for reliable timestamps and measuring short time intervals
accurately. Starts at system boot time but stops during suspend.
ktime_get_real:
Returns the time in relative to the UNIX epoch starting in 1970 using
the Coordinated Universal Time (UTC), same as gettimeofday() user space.
Since ktime_get() returnis time since boot time, this value is
meaningless when compared to those from a different node in cluster, right?
And we need a "__kernel_long_t" to rather than a "u32"?
> + kt = ktime_sub(last, mw->mw_lock_start);
> usec = ktime_to_us(kt);
>
> stats->ls_gets++;
> @@ -474,6 +475,8 @@ static void ocfs2_update_lock_stats(struct ocfs2_lock_res *res, int level,
>
> if (ret)
> stats->ls_fail++;
> +
> + stats->ls_last = ktime_to_timespec(last).tv_sec;
> }
>
Though maybe ocfs2_update_lock_stats() is designed to be called for each
successful lock request,
seems current code calls it even when it returns with -EAGAIN which
breaks the design. That's not introduced by your change, well, it may
lead to wrong stats...
thanks,
wengang
> static inline void ocfs2_track_lock_refresh(struct ocfs2_lock_res *lockres)
> @@ -3093,8 +3096,10 @@ static void *ocfs2_dlm_seq_next(struct seq_file *m, void *v, loff_t *pos)
> * - Lock stats printed
> * New in version 3
> * - Max time in lock stats is in usecs (instead of nsecs)
> + * New in version 4
> + * - Add last pr/ex unlock times in secs
> */
> -#define OCFS2_DLM_DEBUG_STR_VERSION 3
> +#define OCFS2_DLM_DEBUG_STR_VERSION 4
> static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
> {
> int i;
> @@ -3145,6 +3150,8 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
> # define lock_max_prmode(_l) ((_l)->l_lock_prmode.ls_max)
> # define lock_max_exmode(_l) ((_l)->l_lock_exmode.ls_max)
> # define lock_refresh(_l) ((_l)->l_lock_refresh)
> +# define lock_last_prmode(_l) ((_l)->l_lock_prmode.ls_last)
> +# define lock_last_exmode(_l) ((_l)->l_lock_exmode.ls_last)
> #else
> # define lock_num_prmode(_l) (0)
> # define lock_num_exmode(_l) (0)
> @@ -3155,6 +3162,8 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
> # define lock_max_prmode(_l) (0)
> # define lock_max_exmode(_l) (0)
> # define lock_refresh(_l) (0)
> +# define lock_last_prmode(_l) (0)
> +# define lock_last_exmode(_l) (0)
> #endif
> /* The following seq_print was added in version 2 of this output */
> seq_printf(m, "%u\t"
> @@ -3165,6 +3174,8 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
> "%llu\t"
> "%u\t"
> "%u\t"
> + "%u\t"
> + "%u\t"
> "%u\t",
> lock_num_prmode(lockres),
> lock_num_exmode(lockres),
> @@ -3174,7 +3185,9 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
> lock_total_exmode(lockres),
> lock_max_prmode(lockres),
> lock_max_exmode(lockres),
> - lock_refresh(lockres));
> + lock_refresh(lockres),
> + lock_last_prmode(lockres),
> + lock_last_exmode(lockres));
>
> /* End the line */
> seq_printf(m, "\n");
> diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
> index 1f029fbe8b8d..8efa022684f4 100644
> --- a/fs/ocfs2/ocfs2.h
> +++ b/fs/ocfs2/ocfs2.h
> @@ -164,6 +164,7 @@ struct ocfs2_lock_stats {
>
> /* Storing max wait in usecs saves 24 bytes per inode */
> u32 ls_max; /* Max wait in USEC */
> + u32 ls_last; /* Last unlock time in SEC */
> };
> #endif
>
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