From: Srivatsa Vaddagiri <vatsa@in.ibm.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Avi Kivity <avi@redhat.com>, Andi Kleen <andi@firstfloor.org>,
Gleb Natapov <gleb@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org, hpa@zytor.com,
mingo@elte.hu, npiggin@suse.de, tglx@linutronix.de,
mtosatti@redhat.com
Subject: Re: [PATCH] use unfair spinlock when running on hypervisor.
Date: Thu, 3 Jun 2010 11:08:03 +0530 [thread overview]
Message-ID: <20100603053803.GA4035@linux.vnet.ibm.com> (raw)
In-Reply-To: <1275540711.29413.63.camel@edumazet-laptop>
On Thu, Jun 03, 2010 at 06:51:51AM +0200, Eric Dumazet wrote:
> > Guest side:
> >
> > static inline void spin_lock(spinlock_t *lock)
> > {
> > raw_spin_lock(&lock->rlock);
> > + __get_cpu_var(gh_vcpu_ptr)->defer_preempt++;
>
> 1) __this_cpu_inc() should be faster
Ok ..thx for that tip.
> 2) Isnt a bit late to do this increment _after_
> raw_spin_lock(&lock->rlock);
I think so, my worry about doing it earlier is we may set the defer_preempt hint
for the wrong vcpu (if lets say the guest application thread is preempted by
guest kernel and later migrated to another vcpu after it sets the hint and
before it acquires the lock).
- vatsa
next prev parent reply other threads:[~2010-06-03 5:38 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-01 9:35 [PATCH] use unfair spinlock when running on hypervisor Gleb Natapov
2010-06-01 15:53 ` Andi Kleen
2010-06-01 16:24 ` Gleb Natapov
2010-06-01 16:38 ` Andi Kleen
2010-06-01 16:52 ` Avi Kivity
2010-06-01 17:27 ` Andi Kleen
2010-06-02 2:51 ` Avi Kivity
2010-06-02 5:26 ` Srivatsa Vaddagiri
2010-06-02 8:50 ` Andi Kleen
2010-06-02 9:00 ` Avi Kivity
2010-06-03 4:20 ` Srivatsa Vaddagiri
2010-06-03 4:51 ` Eric Dumazet
2010-06-03 5:38 ` Srivatsa Vaddagiri [this message]
2010-06-03 8:52 ` Andi Kleen
2010-06-03 9:26 ` Srivatsa Vaddagiri
2010-06-03 10:22 ` Nick Piggin
2010-06-03 10:38 ` Nick Piggin
2010-06-03 12:04 ` Srivatsa Vaddagiri
2010-06-03 12:38 ` Nick Piggin
2010-06-03 12:58 ` Srivatsa Vaddagiri
2010-06-03 13:04 ` Srivatsa Vaddagiri
2010-06-03 13:45 ` Nick Piggin
2010-06-03 14:48 ` Srivatsa Vaddagiri
2010-06-03 15:17 ` Andi Kleen
2010-06-03 15:35 ` Nick Piggin
2010-06-03 17:25 ` Andi Kleen
2010-06-01 17:39 ` Valdis.Kletnieks
2010-06-02 2:46 ` Avi Kivity
2010-06-02 7:39 ` H. Peter Anvin
2010-06-01 17:54 ` john cooper
2010-06-01 19:36 ` Andi Kleen
2010-06-03 11:06 ` David Woodhouse
2010-06-03 15:15 ` Andi Kleen
2010-06-01 21:39 ` Eric Dumazet
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