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Date: Thu, 16 Mar 2006 17:38:08 -0800
From: Andrew Morton <akpm@osdl.org>
To: Hugh Dickins <hugh@veritas.com>
Cc: rlrevell@joe-job.com, mingo@elte.hu, nickpiggin@yahoo.com.au,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fix free swap cache latency
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Hugh Dickins <hugh@veritas.com> wrote:
>
>  			(*zap_work)--;
>  			continue;
>  		}
> +
> +		(*zap_work) -= PAGE_SIZE;

Sometimes we subtract 1 from zap_work, sometimes PAGE_SIZE.  It's in units
of bytes, so PAGE_SIZE is correct.  Although it would make sense to
redefine it to be in units of PAGE_SIZE.  What's up with that?

Even better, define it in units of "approximate number of touched
cachelines".  After all, it is a sort-of-time-based thing.