Date: Wed, 20 Apr 2005 14:41:25 +0530
From: Srivatsa Vaddagiri <vatsa@in.ibm.com>
To: Nish Aravamudan <nish.aravamudan@gmail.com>
Cc: george@mvista.com, nickpiggin@yahoo.com.au, mingo@elte.hu,
       high-res-timers-discourse@lists.sourceforge.net,
       linux-kernel@vger.kernel.org
Subject: Re: VST and Sched Load Balance
Message-ID: <20050420091125.GB20793@in.ibm.com>
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References: <20050407124629.GA17268@in.ibm.com> <29495f1d0504190907234a0d1d@mail.gmail.com>
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On Tue, Apr 19, 2005 at 09:07:49AM -0700, Nish Aravamudan wrote:
> > +                       if (jiffies - sd1->last_balance >= interval) {


> Sorry for the late reply, but shouldn't this jiffies comparison be
> done with time_after() or time_before()?

I think it is not needed. The check should be able to handle overflow case also.

This probably assumes that you don't sleep longer than (2e32 - 1) jiffies
(which is ~1193 hrs). Current VST implementation let us sleep way less than that
limit (~896 ms) since it uses 32-bit number for sampling TSC. When it is
upgraded to use 64-bit number, we may have to ensure that this limit (1193 hrs)
is not exceeded.

-- 


Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017
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