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Re: [Xen-devel] [PATCH] use atomic_t type for system wide credit schedul

To: "Yang, Xiaowei" <xiaowei.yang@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] use atomic_t type for system wide credit scheduler statistics
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 09 Mar 2009 08:36:06 +0000
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On 09/03/2009 08:30, "Yang, Xiaowei" <xiaowei.yang@xxxxxxxxx> wrote:

> Keir Fraser wrote:
>> Not while csched stats are enabled by default. They get cranked all over the
>> place. How much does this race matter? We probably just lose a few
>> increments?
> Yes. The higher frequency the count is updated, the more increments lost
> can we see - comparing to atomic version, counts like "vcpu_check" and
> "scheduele" lose increments very obviously due to race.

The best thing to do would be to move the stats into perfc_defn.h, don't you
think? The CSCHED_* macro wrappers could be kept but wrap the existing
common mechanism for perf counters.

 -- Keir

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