23.08.2013, 22:08, "David Miller" <davem@xxxxxxxxxxxxx>: > From: Kirill Tkhai <tkhai@xxxxxxxxx> > Date: Fri, 23 Aug 2013 19:43:56 +0400 >> It looks like nobody supports this. I saw an old patch for x86 >> (https://lkml.org/lkml/2003/6/16/226) and several others, but they >> were not integrated. So, sparc64 can be the first. > Exciting, sparc64 is becomming such a groundbreaking platform :-) > >> Other architectures have no as cheap replication as sparc64 has. They must >> modify page table top every switch_to(), while sparc64 is free from this thing. >> And it looks like they have to flush all instruction cache every context switch. >> >> I'll work on the patch a little bit more and test it in different boundary cases, >> before submit it as a ready patch. > I'd be interested in any performance improvement you can show because that's > the reason to do this right? > > A parallel kernel build utilizing all nodes ought to show at least something. I used 16 CPU system with a clock rate of 820 MHz. Test "time make image -j64" gives the following: Before: real 7m58.466s user 60m49.660s sys 47m40.030s After: real 7m55.562s user 60m20.900s sys 46m36.040s So, the real profit (system time) is whole 2.2%. I thought, it would be more :) It seems, it's not big enough to really implement this feature. Practice checks a hypothesis. Thanks for the discussion, David! Regards, Kirill. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
