On Fri, Dec 21, 2012 at 10:58:48PM -0500, Rik van Riel wrote:
> On 12/21/2012 10:49 PM, Steven Rostedt wrote:
> >On Fri, Dec 21, 2012 at 09:51:35PM -0500, Rik van Riel wrote:
>
> >>However, since spinlock contention should not be the
> >>usual state, and all a scalable lock does is make sure
> >>t
On 12/22/2012 12:42 AM, Michel Lespinasse wrote:
However, I have a few concerns about the behavior of this, which I
think deserve more experimentation (I may try helping with it after
new years).
More experimentation is always good. Different hardware
will probably behave differently, etc...
On Fri, Dec 21, 2012 at 3:51 PM, Rik van Riel wrote:
> Subject: x86,smp: auto tune spinlock backoff delay factor
>
> Many spinlocks are embedded in data structures; having many CPUs
> pounce on the cache line the lock is in will slow down the lock
> holder, and can cause system performance to fall
On 12/21/2012 10:49 PM, Steven Rostedt wrote:
On Fri, Dec 21, 2012 at 09:51:35PM -0500, Rik van Riel wrote:
However, since spinlock contention should not be the
usual state, and all a scalable lock does is make sure
that N+1 CPUs does not perform worse than N CPUs, using
scalable locks is a st
On Fri, Dec 21, 2012 at 09:51:35PM -0500, Rik van Riel wrote:
> On 12/21/2012 07:47 PM, David Daney wrote:
>
> >>+#define MIN_SPINLOCK_DELAY 1
> >>+#define MAX_SPINLOCK_DELAY 1000
> >>+DEFINE_PER_CPU(int, spinlock_delay) = { MIN_SPINLOCK_DELAY };
> >
> >
> >This gives the same delay for all locks
On 12/21/2012 07:47 PM, David Daney wrote:
+#define MIN_SPINLOCK_DELAY 1
+#define MAX_SPINLOCK_DELAY 1000
+DEFINE_PER_CPU(int, spinlock_delay) = { MIN_SPINLOCK_DELAY };
This gives the same delay for all locks in the system, but the amount of
work done under each lock is different. So, for an
On 12/21/2012 03:51 PM, Rik van Riel wrote:
Subject: x86,smp: auto tune spinlock backoff delay factor
Nice work,
A couple of comments...
Many spinlocks are embedded in data structures; having many CPUs
pounce on the cache line the lock is in will slow down the lock
holder, and can cause sys
Subject: x86,smp: auto tune spinlock backoff delay factor
Many spinlocks are embedded in data structures; having many CPUs
pounce on the cache line the lock is in will slow down the lock
holder, and can cause system performance to fall off a cliff.
The paper "Non-scalable locks are dangerous" is
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