Messages in this thread | | | Date | Tue, 27 Jul 2010 10:32:54 -0700 | From | Patrick Pannuto <> | Subject | Re: [PATCH] checkpatch: Add warnings for use of mdelay() |
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On 07/27/2010 10:31 AM, Jonathan Corbet wrote: > On Tue, 27 Jul 2010 10:11:11 -0700 > Israel Schlesinger <israels@codeaurora.org> wrote: > >> mdelay is a busy-wait loop which is wasteful. If at all possible, >> callers should use msleep instead of mdelay. >> >> The only time mdelay is really appropriate is in atomic context, >> however, delays of 1ms+ in atomic context are rather expensive, so >> a warning for this case is probably appropriate as well to encourage >> people to move such expensive delays outside of atomic context > > Once upon a time, msleep(1) would sleep for 20ms, while mdelay(1) gave > a 1ms delay. My patch to fix msleep() at that time didn't get in due > to concerns about the cost of using hrtimers. Perhaps msleep() has > gotten better, but, if not, actually getting a 1ms delay remains a > valid reason for using mdelay() instead IMO. It made a difference of a > few seconds at open time for a driver I was doing at the time. > > jon > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
Check out the recently added usleep in -tip, and the checkpatch patch pending in my queue that fixes that case (I'll send in a few hours ;) )
-pat
-- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
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