Re: Separating bgwriter and checkpointer

On 20.09.2011 17:31, Cédric Villemain wrote:
> 2011/9/20 Heikki Linnakangas<heikki(dot)linnakangas(at)enterprisedb(dot)com>:
>> On 20.09.2011 16:49, Magnus Hagander wrote:
>>>
>>> Isn't there also the advantage of that work put in two different
>>> processes can use two different CPU cores? Or is that likely to never
>>> ever come in play here?
>>
>> You would need one helluva I/O system to saturate even a single CPU, just by
>> doing write+fsync.
>
> The point of Magnus is valid. There are possible throttling done by
> linux per node, per process/task.
> Since ..2.6.37 (32 ?) I believe .. there are more temptation to have
> have per cgroup io/sec limits, and there exists some promising work
> done to have a better IO bandwith throttling per process.
>
> IMO, splitting the type of IO workload per process allows the
> administrators to have more control on the IO limits they want to have
> (and it may help the kernels() to have a better strategy ?)

That is a separate issue from being able to use different CPU cores. But
cool! I didn't know Linux can do that nowadays. That could be highly
useful, if you can put e.g autovacuum on a different cgroup from regular
backends.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com