On Wed, Aug 06, 2014 at 01:41:30AM +0400, Kirill Tkhai wrote: > Hi, IA64 Gurus, > > I was looking for the reasons of IA64's __ARCH_WANT_UNLOCKED_CTXSW, > and found the historical commit below: > > commit f8efa27662532ad5adb2790bfc3f4c78e019cfad > Author: Chen, Kenneth W <kenneth.w.chen@xxxxxxxxx> > Date: Thu Jan 26 18:24:59 2006 -0800 > > [IA64] remove staled comments in asm/system.h > > With the recent optimization made to wrap_mmu_context function, > we don't hold tasklist_lock anymore when wrapping context id. > The comments in asm/system.h must fall through the crack earlier. > Remove staled comments. > > I believe it is still beneficial to unlock the runqueue lock > across context switch. So leave __ARCH_WANT_UNLOCKED_CTXSW on. > > Signed-off-by: Ken Chen <kenneth.w.chen@xxxxxxxxx> > Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx> > > The comment confuses a reader. It may seem that the #define > is not necessary now, no comment around it at all. > > So, could you please point the deadlock we want to avoid > by __ARCH_WANT_UNLOCKED_CTXSW? I've tried to find, but nothing > was found by me. No IA64 machines around, so I can't just > to load kernel w/o this define. see http://marc.info/?l=linux-kernel&m=131418885605812
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