Quoting r. Libor Michalek <[EMAIL PROTECTED]>: > Subject: Re: [PATCH] sdp: replace mlock with get_user_pages > > On Thu, May 05, 2005 at 02:01:58PM +0300, Michael S. Tsirkin wrote: > > Hello, Libor! > > The following patch replaces the mlock hack with call > > to get_user_pages. Since the application could have forked > > while an iocb is outstanding, when an iocb is done > > I do get_user_pages for a second time and copy data if > > the physical address has changed. > > > > Thus, changing ulimit is no longer required to get aio > > working, processes are also allowed to fork and to call mlock/munlock > > on the buffer. > > > > Tested by the ttcp.aio benchmark, and works fine for me. > > In the latest kernel what happens to a page that's held > with a get_user_page reference on fork? Which is the only > case left.
I dont think there's a change - the only other way to handle this is to block fork until an iocb is complete. > Since there is an iocv flag parameter it would > be prefered to use a bit there instead of is_receive. Also, > please leave spaces around '='. I'll try to address these. > Finally it would be nice > if we could get rid of having to schedule a task to unlock > the iocb in complete, I've noticed this having a negative > effect on system CPU utilization on older kernels. > > -Libor Even we get around the fact that get user pages needs an mm semaphore, its still nontrivial since set_page_dirty_lock might sleep. MST -- MST - Michael S. Tsirkin _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
