On Thu, Aug 24, 2006 at 08:38:38PM +0900, Atsushi Nemoto wrote: > Date: Thu, 24 Aug 2006 20:38:38 +0900 (JST) > To: ralf@xxxxxxxxxxxxxx > Cc: nigel@xxxxxxxx, linux-mips@xxxxxxxxxxxxxx > Subject: Re: [PATCH] fix cache coherency issues > From: Atsushi Nemoto <anemo@xxxxxxxxxxxxx> > Content-Type: Text/Plain; charset=us-ascii > > On Thu, 24 Aug 2006 12:15:15 +0100, Ralf Baechle <ralf@xxxxxxxxxxxxxx> wrote: > > Your patch also still contains copy_user_page(). The only user of it used > > to be copy_user_highpage() so after our rewrite it can go away. I've > > already applied both fixes to my working version of the patch. > > Yes, it is intentional. I keep copy_user_page() just because it is > described in cachetlb.txt and exported. > > Of course we can remove it. I do not care :-) Also I wondered we > should export copy_user_highpage() or not ... > > > Your patch only maps the source page. I'm trying to map the destination > > page also and I'm hitting a few issues with it. > > If you wanted to map the destination, you must writeback the dcache > via kernel mapping first. The dcache can contain dirty data for the > page by previous usage. And if the page was executable, we must flush > the destination page after copy_page() (via coherent mapping) anyway > for I/D coherency. > > So now I think mapping the destination is not worth to do. I figured it was worth a try. It means the process will start running with a hot copy of the COW page instead of a cold copy and I can use hit invalidates instead of hit wbinv on the kernel address of the to page. Lmbenching now, stay tuned ... Ralf
