On 10/02/13 10:14, Santosh Shilimkar wrote: > On Wednesday 02 October 2013 01:09 PM, Will Deacon wrote: >> On Wed, Oct 02, 2013 at 05:55:28PM +0100, Santosh Shilimkar wrote: >>> The sched_clock code uses 2 levels of function pointers, sched_clock_func() >>> and read_sched_clock() but the no sched_clock check in postinit() just >>> checks read_sched_clock(). >>> >>> This leads to kernel falling back to jiffy based sched clock even in >>> presence of sched_clock_func() which is not desirable. >>> >>> Fix the postinit() check to avoid the issue. Probably the issue is hidden >>> so far on most of the arm SOCs because of already existing sched_clock >>> registrations apart from arch_timer sched_clock. One can reproduce the >>> issue by just have arch_timer as sched_clock >> Isn't this just an issue with the arch timer driver not calling >> setup_sched_clock? Instead, we munge around with sched_clock_func directly, >> which doesn't appear to be the way anybody else deals with this. >> > I thought about that option as well but was not sure since even in that case > the check is not complete. We just ensure that function is popullated.
Yes, nothing is actually broken because sched_clock_func() won't try to use the jiffy based read_sched_clock() function. I'm not sure we actually need this patch besides to remove a useless timer that updates the jiffy epoch. Can we wait until my 64-bit sched_clock patch series lands in 3.13? It looks like I still need an ack from Will or Catalin on the architected timer patch before the clocksource folks pick it up. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
