Re: let's make libpager single-threaded

[Samuel Thibault]

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.

Samuel