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List:       linux-kernel
Subject:    Re: [ck] Re: [PATCH] vm - swap_prefetch-15
From:       Gustavo Barbieri <barbieri () gmail ! com>
Date:       2005-10-07 14:44:00
Message-ID: 9ef20ef30510070744l7ff1f1bbweb4da1ceb513f246 () mail ! gmail ! com
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On 10/7/05, Pekka Enberg <penberg@cs.helsinki.fi> wrote:
> Hi,
>
> On 10/7/05, Con Kolivas <kernel@kolivas.org> wrote:
> > Good point, thanks! Any and all feedback is appreciated.
>
> Well, since you asked :-)
>
> > +/*
> > + * How many pages to prefetch at a time. We prefetch SWAP_CLUSTER_MAX *
> > + * swap_prefetch per PREFETCH_INTERVAL, but prefetch ten times as much at a
> > + * time in laptop_mode to minimise the time we keep the disk spinning.
> > + */
> > +#define PREFETCH_PAGES()     (SWAP_CLUSTER_MAX * swap_prefetch * \
> > +                                     (1 + 9 * laptop_mode))
>
> This looks strange. Please either drop the parenthesis from PREFETCH_PAGES or
> make it a real static inline function.

Or make it a "const static" variable, so compiler will check types and
everything, but the symbol will not be present in the binary, causing
no overhead. So it could be:

const unsigned PREFETCH_PAGES = (SWAP_CLUSTER_MAX * swap_prefetch * \
        (1 + 9 * laptop_mode));

--
Gustavo Sverzut Barbieri
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