From: Keir Fraser <keir.xen@gmail.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Simon Martin <smartin@milliways.cl>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: VCPUOP_set_periodic_timer
Date: Fri, 15 Nov 2013 13:39:31 +0000 [thread overview]
Message-ID: <CEABD493.3F379%keir.xen@gmail.com> (raw)
In-Reply-To: <52861DE8.5060208@citrix.com>
On 15/11/2013 13:13, "Andrew Cooper" <andrew.cooper3@citrix.com> wrote:
>
> On 15/11/13 13:10, Keir Fraser wrote:
>
>
>> Re: Re[4]: [Xen-devel] VCPUOP_set_periodic_timer You¹ll have to measure to
>> confirm, but if the core is dedicated to your vcpu then there is no reason
>> there should be 50us jitter. Also there is not much point playing with
>> different schedulers ‹ if there are no other vcpus schedulable on the cpu,
>> the scheduler can¹t have multiple runnable vcpus to choose between.
>>
>> -- Keir
>>
>
> The deadline timer code as up to 50us of slop when calculating when to wake
> up and when timers expire. It is somewhat poor, and is certainly an area in
> need of improvement.
Forgot about that. For real-time applications, timer_slop=0 on the Xen
command line will turn it off. But there could certainly be other gotchas
lurking; actual performance needs to be measured.
-- Keir
> ~Andrew
>
next prev parent reply other threads:[~2013-11-15 13:39 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-14 21:18 VCPUOP_set_periodic_timer Simon Martin
2013-11-14 21:39 ` VCPUOP_set_periodic_timer Andrew Cooper
2013-11-15 11:24 ` VCPUOP_set_periodic_timer Simon Martin
2013-11-15 11:36 ` VCPUOP_set_periodic_timer Keir Fraser
2013-11-15 11:45 ` VCPUOP_set_periodic_timer Simon Martin
2013-11-15 11:56 ` VCPUOP_set_periodic_timer Keir Fraser
2013-11-15 12:37 ` VCPUOP_set_periodic_timer Simon Martin
2013-11-15 13:10 ` VCPUOP_set_periodic_timer Keir Fraser
2013-11-15 13:13 ` VCPUOP_set_periodic_timer Andrew Cooper
2013-11-15 13:39 ` Keir Fraser [this message]
2013-11-15 11:41 ` VCPUOP_set_periodic_timer Andrew Cooper
2013-11-15 12:02 ` VCPUOP_set_periodic_timer Simon Martin
2013-11-15 12:17 ` VCPUOP_set_periodic_timer Andrew Cooper
2013-11-15 12:46 ` VCPUOP_set_periodic_timer Nate Studer
2013-11-15 12:52 ` VCPUOP_set_periodic_timer Andrew Cooper
2013-11-15 12:54 ` VCPUOP_set_periodic_timer George Dunlap
2013-11-15 21:10 ` VCPUOP_set_periodic_timer Dario Faggioli
2013-11-16 20:37 ` VCPUOP_set_periodic_timer Simon Martin
2013-11-18 18:28 ` VCPUOP_set_periodic_timer Dario Faggioli
2013-11-26 14:50 ` PV guest timings Simon Martin
2013-11-26 15:11 ` Keir Fraser
2013-11-26 15:38 ` Simon Martin
2013-11-26 23:33 ` Dario Faggioli
2013-11-27 2:32 ` Simon Martin
2013-11-27 8:46 ` Dario Faggioli
2013-11-27 12:04 ` Simon Martin
2013-11-27 10:38 ` David Vrabel
2013-11-27 14:07 ` Simon Martin
2013-11-26 23:31 ` Dario Faggioli
2013-11-27 2:36 ` Simon Martin
2013-11-27 8:56 ` Dario Faggioli
2013-11-27 13:00 ` Simon Martin
2013-11-28 11:16 ` Dario Faggioli
2013-11-28 11:57 ` Simon Martin
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