On Tue, Nov 20, 2012 at 12:08 AM, Jeff Davis <pg...@j-davis.com> wrote:
> On Mon, 2012-11-19 at 23:50 +0530, Atri Sharma wrote: > > > Sorry If I am being a bit naive, but shouldnt a simple mutex work in > > the case when a process wants to change the VM bit in cache? > > > > Mutex would be cheaper than locks. > > > I thought mutexes are locks? > > The point is to avoid taking new locks (or mutexes) during a read of the > VM bit, because there is concern that it could cause contention. If we > lock the entire VM page, that represents many, many data pages, so it's > worrisome. > > Regards, > Jeff Davis > > > My mistake...I thought we were more concerned about the cost of locking. I agree, locking many data pages simultaneously could be hazardous. This requires more thought.Maybe removing PD_ALL_VISIBLE isnt such a great idea after all... Atri -- Regards, Atri *l'apprenant*
