Messages in this thread | | | Date | Tue, 25 Mar 2008 21:42:23 -0700 | From | Arjan van de Ven <> | Subject | Re: [Bug 10328] New: [regression] performance drop for glx |
| |
Suresh Siddha wrote: > On Tue, Mar 25, 2008 at 03:28:09PM -0700, Andrew Morton wrote: >> (switched to email. Please respond via emailed reply-to-all, not via the >> bugzilla web interface). >> >> On Tue, 25 Mar 2008 15:11:15 -0700 (PDT) >> bugme-daemon@bugzilla.kernel.org wrote: >> >>> http://bugzilla.kernel.org/show_bug.cgi?id=10328 >>> >>> Summary: [regression] performance drop for glx >>> >>> after commit 4138cc3418f5eaa7524ff8e927102863f1ba0ea5 i expirience some grafik >>> related perfomance issues. >>> >>> I used glxgears for test. >>> before this patch: 1281.005 FPS >>> and after: 765.000 FPS >> It nearly halved. >> >>> latest tested commit a4083c9271e0a697278e089f2c0b9a95363ada0a >>> still hase bad performance. >>> >>> I use Pentium D with 2GB RAM, Grafick: i945G, ICH7 >>> >> That's >> >> : commit 4138cc3418f5eaa7524ff8e927102863f1ba0ea5 >> : Author: Siddha, Suresh B <suresh.b.siddha@intel.com> >> : Date: Wed Jan 30 13:33:43 2008 +0100 >> : >> : x86: set strong uncacheable where UC is really desired >> : >> : Also use _PAGE_PWT for all the mappings which need uncache mapping. >> : Instead of existing PAT2 which is UC- (and can be overwritten by MTRRs), >> : we now use PAT3 which is strong uncacheable. >> : >> : This makes it consistent with pgprot_noncached() > > Alexey, Can you please try the appended patch? > > Andrew, can you please push the appended patch for 2.6.25? Thanks. > --- > > fb drivers are using ioremap()/ioremap_nocache(), followed by mtrr_add with > WC attribute. Recent changes in page attribute code made both > ioremap()/ioremap_nocache() mappings as UC (instead of previous UC-). This > breaks the graphics performance, as the effective memory type is UC instead > of expected WC. > > The correct way to fix this is to add ioremap_wc() (which uses UC- in the > absence of PAT kernel support and WC with PAT) and change all the > fb drivers to use this new ioremap_wc() API. > > We can take this correct and longer route for post 2.6.25. For now, > revert back to the UC- behavior for ioremap/ioremap_nocache.
I would still like to add an ioremap_wc() even in 2.6.25; even if it's for now identical to ioremap_nocache(). Better get the right API in place as soon as possible
| |