From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCHv3 0/4] Use ticket locks for spinlocks
Date: Thu, 23 Apr 2015 13:42:46 +0100
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To: Jan Beulich <JBeulich@suse.com>, David Vrabel <david.vrabel@citrix.com>, Jennifer Herbert <jennifer.herbert@citrix.com>
Cc: Keir Fraser <keir@xen.org>, Ian Campbell <ian.campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Tim Deegan <tim@xen.org>, xen-devel@lists.xenproject.org
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On 21/04/15 11:22, Jan Beulich wrote:
>>>> On 21.04.15 at 12:11, <david.vrabel@citrix.com> wrote:
>> We have analysed the affect of this series on interrupt latency (by
>> measuring the duration of irq disable/enable regions) and there is no
>> signficant impact.
>>
>> http://xenbits.xen.org/people/dvrabel/bar2_comp.png 
> 
> Thanks for doing this!
> 
>> Interestingly, the biggest offenders for long critical sections are
>> bare irq disable/enable regions, and some of these are really bad (10s
>> of ms)!
>>
>> http://xenbits.xen.org/people/dvrabel/bar_normal_busy.png 
> 
> Despite both pictures saying micro-seconds at the respective
> axis (and hence the problem not being _as bad_)

This particular graph doesn't show it very well but there are small
blips around 4, 10, and 31 ms.

David