Messages in this thread | | | Date | Sat, 15 Sep 2012 19:08:59 +0200 | Subject | Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets - bisected | From | richard -rw- weinberger <> |
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On Sat, Sep 15, 2012 at 6:36 PM, Mike Galbraith <efault@gmx.de> wrote: >> Just using futex is unfortunately not the answer either. > > Yes, postgress performs loads better with it's spinlocks, but due to > that, it necessarily _hates_ preemption. How the is the scheduler > supposed to know that any specific userland task _really_ shouldn't be > preempted at any specific time, else bad things follow?
Why perform custom userspace spinlocks better than futex() based ones? I thought we have futex() to get rid of the custom ones... Makes futex() only sense when things like priority inheritance are needed?
-- Thanks, //richard
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