Re: let's make libpager single-threaded

[Richard Braun]

On Fri, May 30, 2014 at 08:15:43PM +0200, Samuel Thibault wrote:
> Justus Winter, le Fri 30 May 2014 09:35:37 +0200, a écrit :
> > Quoting Richard Braun (2014-05-29 19:12:13)
> > > On Thu, May 29, 2014 at 07:04:48PM +0200, Samuel Thibault wrote:
> > > > But precisely: once the only thread gets a data_request, it'll call
> > > > pager_read_page, which will typically call store_read, which will wait
> > > > on the eventual I/O, and no other request will be processed during that
> > > > time, and thus not pipelining the I/O requests.
> > > 
> > > Right, I assumed the store interface wasn't synchronous...
> > 
> > So we want a fixed number of pager threads?
> 
> We can use a fixed number of pager threads, yes.  Perhaps just 1 indeed
> currently gives the best performance because the device backends that we
> currently use don't get benefit from piling up requests.  But at least
> we keep the infrastructure to pile up requests for when we fix the
> backends.

Agreed.

-- 
Richard Braun