On Thu, Mar 3, 2011 at 9:50 AM, KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
Thanks very much for your comments.
Yeah, we'er going to try tracepoint and perf as Ingo said.
This is the starting point of the patch set, so I simply embedded the structure into the existing infrastructure. This did saved me a lot of effort because disk_stats is a good place to collect stats on _partition_ basis. Anyway, as you pointed out, this is kind of the mess.
> [Summery]I think you need to explain exact and concrete use-case. Typically,
>
> In order to evaluate page cache efficiency, system admins are happy to
> know whether a block of data is cached for subsequent use, or whether
> the page is read-in but seldom used. This patch extends an effort to
> provide such kind of information. We adds three counters, which are
> exported to the user space, for the Page Cache that is almost
> transparent to the applications. This would benifit some heavy page
> cache users that might try to tune the performance in hybrid storage
> situation.
cache-hit ratio doesn't help administrator at all. because merely backup
operation (eg. cp, dd, et al) makes prenty cache-miss. But it is no sign
of memory shortage. Usually, vmscan stastics may help memroy utilization
obzavation.
Plus, as ingo said, you have to consider to use trancepoint framework
at first. Because, it is zero cost if an admin don't enable such tracepoint.
Thanks very much for your comments.
Yeah, we'er going to try tracepoint and perf as Ingo said.
At last, I don't think disk_stats have to have page cache stastics. It seems
slightly layer violation.
Thanks.
This is the starting point of the patch set, so I simply embedded the structure into the existing infrastructure. This did saved me a lot of effort because disk_stats is a good place to collect stats on _partition_ basis. Anyway, as you pointed out, this is kind of the mess.
Thanks,
Yuan