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Date: Tue, 21 Apr 2009 17:05:15 -0700 From: john stultz <johnstul@...ibm.com> To: Jon Hunter <jon-hunter@...com> Cc: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [RFC][PATCH] Dynamic Tick: Allow 32-bit machines to sleep for more than 2.15 seconds On Tue, 2009-04-21 at 18:20 -0500, Jon Hunter wrote: > john stultz wrote: > > The concern is many clocksources wrap after a handful of seconds. The > > acpi_pm is the best example (its only 24 bits wide). > > > > I brought this issue up earlier, and provided some example code that > > could be used to limit the idle time appropriately for the current > > clocksource here: > > > > http://lkml.indiana.edu/hypermail/linux/kernel/0901.3/02693.html > > > > Jon: Did you see that mail, or is there a reason you didn't adapt this > > code into your patch? > > Hi John, yes I did read this email and thanks for bringing this up. > > As I looked at this more I noticed that for 64-bit machines that the > max_delta_ns would be a 64-bit integer already and so this change would > only have an impact for 32-bit machines. I understand that there are > more 32-bit machines that 64-bit. However, I was trying to understand > how the wrapping of clocksources, such as the one you mention above, is > handled today for 64-bit machines that could theoretically sleep for > longer periods. One other minor comment nit, if we're really meaning that max_delta_ns is a 64bit value, should we not just be using s64 and be explicit instead of converting longs to long longs? thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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