linux-kernel - Re: [PATCH] sched: Provide iowait counters

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 24 Jul 2009 21:48:22 -0700
From:	Arjan van de Ven <arjan@...ux.intel.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	"Kok, Auke-jan H" <auke-jan.h.kok@...el.com>
Subject: Re: [PATCH] sched: Provide iowait counters

Andrew Morton wrote:
> On Fri, 24 Jul 2009 21:33:02 -0700 Arjan van de Ven <arjan@...ux.intel.com> wrote:
> 
>> Andrew Morton wrote:
>>> On Mon, 20 Jul 2009 11:31:47 -0700 Arjan van de Ven <arjan@...ux.intel.com> wrote:
>>>
>>>> For counting how long an application has been waiting for (disk) IO,
>>>> there currently is only the HZ sample driven information available, while
>>>> for all other counters in this class, a high resolution version is
>>>> available via CONFIG_SCHEDSTATS.
>>>>
>>>> In order to make an improved bootchart tool possible, we also need
>>>> a higher resolution version of the iowait time.
>>>>
>>>> This patch below adds this scheduler statistic to the kernel.
>>> Doesn't this duplicate the delay accounting already available via the
>>> taskstats interface?
>> we have how long we wait. we do not have how long we iowait afaik...
>> at least not in nanosecond granularity. (We do have the sampled data, but that
>> is milisecond sampled data, not very useful for making charts based on time
>> to show the sequence of events)
> 
> See include/linux/sched.h's definition of task_delay_info - u64
> blkio_delay is in nanoseconds.  It uses
> do_posix_clock_monotonic_gettime() internally.

looks like it does.. to bad we don't expose that data in a /proc/<pid>/delay or something field
like we do with the scheduler info...


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/