<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - [SKL GT4e] large perf drop (up to 27%) in most 3D benchmarks" href="https://bugs.freedesktop.org/show_bug.cgi?id=111731#c4">Comment # 4</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - [SKL GT4e] large perf drop (up to 27%) in most 3D benchmarks" href="https://bugs.freedesktop.org/show_bug.cgi?id=111731">bug 111731</a> from <a class="email" href="mailto:eero.t.tamminen@intel.com" title="Eero Tamminen <eero.t.tamminen@intel.com>"> Eero Tamminen</a> <pre>(In reply to Chris Wilson from <a href="show_bug.cgi?id=111731#c3">comment #3</a>) > > (Why IOMMU perf impact would be SKL GT4e specific?) > > My guess at this moment would be that eDRAM feels the hit more > significantly. Or that we've just got the caching completely wrong on that > sku. We were supposed to have VT-d disabled from BIOS in all our machines, but apparently that had been enabled when SkullCanyon was in other use for a while. I.e. it was only machine with VT-d enabled. > 20+% regression is also in line with some kbl (gt3e iirc) media runs I did. Media, not 3D? (That's more than I saw on SkullCanyon in media test-cases.) I've now enabled VT-d on few other machines (BDW GT2, BXT, SKL GT2, KBL GT3e) to get you a bit more perf info. I'll add that info here later this week.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>