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Date: Fri, 22 Feb 2013 15:37:42 +0530 From: Santosh Shilimkar <santosh.shilimkar@...com> To: Thomas Gleixner <tglx@...utronix.de> CC: Jason Liu <liu.h.jason@...il.com>, LKML <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>, Lorenzo Pieralisi <lorenzo.pieralisi@....com> Subject: Re: too many timer retries happen when do local timer swtich with broadcast timer Thomas, On Friday 22 February 2013 03:49 AM, Thomas Gleixner wrote: > On Thu, 21 Feb 2013, Santosh Shilimkar wrote: >> On Thursday 21 February 2013 07:18 PM, Thomas Gleixner wrote: >>> find below a completely untested patch, which should address that issue. >>> >> After looking at the thread, I tried to see the issue on OMAP and could >> see the same issue as Jason. > > That's interesting. We have the same issue on x86 since 2007 and > nobody noticed ever. It's basically the same problem there, but it > seems that on x86 getting out of those low power states is way slower > than the minimal reprogramming delta which is used to enforce the > local timer to fire after the wakeup. > > I'm still amazed that as Jason stated a 1us reprogramming delta is > sufficient to get this ping-pong going. I somehow doubt that, but > maybe ARM is really that fast :) > >> Your patch fixes the retries on both CPUs on my dual core machine. So >> you use my tested by if you need one. > > They are always welcome. > BTW, Lorenzo off-list mentioned to me about warning in boot-up which I missed while testing your patch. It will take bit more time for me to look into it and hence thought of reporting it. [ 2.186126] ------------[ cut here ]------------ [ 2.190979] WARNING: at kernel/time/tick-broadcast.c:501 tick_broadcast_oneshot_control+0x1c0/0x21c() [ 2.200622] Modules linked in: [ 2.203826] [<c001bfe4>] (unwind_backtrace+0x0/0xf0) from [<c0047d6c>] (warn_slowpath_common+0x4c/0x64) [ 2.213653] [<c0047d6c>] (warn_slowpath_common+0x4c/0x64) from [<c0047da0>] (warn_slowpath_null+0x1c/0x24) [ 2.223754] [<c0047da0>] (warn_slowpath_null+0x1c/0x24) from [<c009336c>] (tick_broadcast_oneshot_control+0x1c0/0x21c) [ 2.234924] [<c009336c>] (tick_broadcast_oneshot_control+0x1c0/0x21c) from [<c00928dc>] (tick_notify+0x23c/0x42c) [ 2.245666] [<c00928dc>] (tick_notify+0x23c/0x42c) from [<c0539a3c>] (notifier_call_chain+0x44/0x84) [ 2.255218] [<c0539a3c>] (notifier_call_chain+0x44/0x84) from [<c0071068>] (raw_notifier_call_chain+0x18/0x20) [ 2.265686] [<c0071068>] (raw_notifier_call_chain+0x18/0x20) from [<c0091c70>] (clockevents_notify+0x2c/0x174) [ 2.276123] [<c0091c70>] (clockevents_notify+0x2c/0x174) from [<c0035294>] (omap_enter_idle_smp+0x3c/0x120) [ 2.286315] [<c0035294>] (omap_enter_idle_smp+0x3c/0x120) from [<c042e504>] (cpuidle_enter+0x14/0x18) [ 2.295928] [<c042e504>] (cpuidle_enter+0x14/0x18) from [<c042ef14>] (cpuidle_wrap_enter+0x34/0xa0) [ 2.305389] [<c042ef14>] (cpuidle_wrap_enter+0x34/0xa0) from [<c042eb20>] (cpuidle_idle_call+0xe0/0x328) [ 2.315307] [<c042eb20>] (cpuidle_idle_call+0xe0/0x328) from [<c0015100>] (cpu_idle+0x8c/0x11c) [ 2.324401] [<c0015100>] (cpu_idle+0x8c/0x11c) from [<c073d7ac>] (start_kernel+0x2b0/0x300) [ 2.333129] ---[ end trace 6fe1f7b4606a9e20 ]--- -- 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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