Re: [Lsf] Preliminary Agenda and Activities for LSF

Chad Talbott
2011-03-29T20:14:19Z

On Tue, Mar 29, 2011 at 12:09 PM, Vivek Goyal <vgoyal@redhat.com> wrote:
> On Tue, Mar 29, 2011 at 10:35:13AM -0700, Chad Talbott wrote:
>> I'd like to propose a discussion topic:
>>
>> IO-less Dirty Throttling Considered Harmful...
>>
>
> I see that writeback has extended session at 10.00. I am assuming
> IO less throttling will be discussed there. Is it possible to
> discuss its effect on block cgroups there? I am not sure enough
> time is there because it ties in memory cgroup also.
>
> Or there is a session at 12.30 "memcg dirty limits and writeback", it
> can probably be discussed there too.

I just want to make sure that the topic is discussed and I don't want
to eat into someone else's time. I'll be sure to bring it up if it's
not granted a dedicated session.

>> to isolation and cgroup IO schedulers in general.  The disk scheduler
>> is knocked out of the picture unless it can see the IO generated by
>> each group above it.  The world of memcg-aware writeback stacked on
>> top of block-cgroups is a complicated one.  Throttling in
>> balance_dirty_pages() will likely be a non-starter for current users
>> of group-aware CFQ.
>
> Can't a single flusher thread keep all the groups busy/full on slow
> SATA device.

A single flusher thread *could* keep all the groups busy and full, but
the current implementation does nothing explicit to make that happen.
I'd like to make sure that this case is considered, independent of a
particular implementation.

Chad
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