From: Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
To: Daniel Kurtz <djkurtz-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Cc: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>,
Olof Johansson <olofj-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Benson Leung <bleung-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Doug Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Linux I2C <linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH] i2c: i2c-s3c2410: Remove recently introduced performance overheads
Date: Tue, 20 Nov 2012 18:48:10 +0900 [thread overview]
Message-ID: <20121120094808.GE10560@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <CAGS+omAkOwq7m_zGCYjwgrFY_jjNfWqvFqS29F5b6GBPr62UFg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
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On Tue, Nov 20, 2012 at 05:45:55PM +0800, Daniel Kurtz wrote:
> On Tue, Nov 20, 2012 at 1:57 PM, Mark Brown
> > + spins = 3;
> > + do {
> > + cpu_relax();
> > + iicstat = readl(i2c->regs + S3C2410_IICSTAT);
> > + } while ((iicstat & S3C2410_IICSTAT_START) && --spins);
> Can you avoid one cpu_relax() by reading IICSTAT first, and switch to
> while { } instead of do { } while ()?
Of course. The CPUs that care about this are single core so the
cpu_relax() has no effect on them anyway.
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next prev parent reply other threads:[~2012-11-20 9:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-20 5:57 [PATCH] i2c: i2c-s3c2410: Remove recently introduced performance overheads Mark Brown
[not found] ` <1353391041-28943-1-git-send-email-broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
2012-11-20 9:45 ` Daniel Kurtz
[not found] ` <CAGS+omAkOwq7m_zGCYjwgrFY_jjNfWqvFqS29F5b6GBPr62UFg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-20 9:48 ` Mark Brown [this message]
-- strict thread matches above, loose matches on Subject: below --
2012-11-21 4:12 Mark Brown
[not found] ` <1353471131-23975-1-git-send-email-broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
2012-11-21 5:08 ` Olof Johansson
[not found] ` <CAOesGMhBZo6gKfzs1A954a_vaAMzy4px3TsgKE2rac_igH3sLw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-21 6:23 ` Daniel Kurtz
2012-11-22 21:35 ` Wolfram Sang
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