Messages in this thread | | | From | Kirill Korotaev <> | Date | Thu, 5 Feb 2009 10:51:34 +0300 | Subject | Re: [git pull] timer fix |
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ACK, it works. Why not save another 4 bytes of .bss then by changing hept_t1_cmp to u32? ;-)
Kirill
On 2/5/09 1:58 AM, "Ingo Molnar" <mingo@elte.hu> wrote:
> > > * Linus Torvalds <torvalds@linux-foundation.org> wrote: > >> } while ((s32)(hpet_readl(HPET_COUNTER) - hpet_t1_cmp) > 0); > > that is also more efficient code by 6 bytes: > > before: > > ffffffff81020856: ff c3 inc %ebx > ffffffff81020858: 48 05 f0 00 00 00 add $0xf0,%rax > ffffffff8102085e: 8b 00 mov (%rax),%eax > ffffffff81020860: 8b 15 2a 79 85 00 mov 0x85792a(%rip),%edx > # ffffffff81878190 <hpet_t1_cmp> > ffffffff81020866: 89 c0 mov %eax,%eax > ffffffff81020868: 48 29 d0 sub %rdx,%rax > ffffffff8102086b: 48 85 c0 test %rax,%rax > ffffffff8102086e: 7f bf jg ffffffff8102082f > <hpet_rtc_interrupt+0x68> > ffffffff81020870: 85 db test %ebx,%ebx > > after: > > ffffffff81020856: ff c3 inc %ebx > ffffffff81020858: 48 05 f0 00 00 00 add $0xf0,%rax > ffffffff8102085e: 8b 00 mov (%rax),%eax > ffffffff81020860: 2b 05 2a 79 85 00 sub 0x85792a(%rip),%eax > # ffffffff81878190 <hpet_t1_cmp> > ffffffff81020866: 85 c0 test %eax,%eax > ffffffff81020868: 7f c5 jg ffffffff8102082f > <hpet_rtc_interrupt+0x68> > ffffffff8102086a: 85 db test %ebx,%ebx > > Kirill, Pavel, could you please re-test the updated commit attached below? > > Ingo > > ----------------> > From 66a36a1e95fe9de9c6a56f0bcd01f4ba21929f86 Mon Sep 17 00:00:00 2001 > From: Pavel Emelyanov <xemul@openvz.org> > Date: Wed, 4 Feb 2009 13:40:31 +0300 > Subject: [PATCH] x86: fix hpet timer reinit for x86_64 > > There's a small problem with hpet_rtc_reinit function - it checks > for the: > > hpet_readl(HPET_COUNTER) - hpet_t1_cmp > 0 > > to continue increasing both the HPET_T1_CMP (register) and the > hpet_t1_cmp (variable). > > But since the HPET_COUNTER is always 32-bit, if the hpet_t1_cmp > is 64-bit this condition will always be FALSE once the latter hits > the 32-bit boundary, and we can have a situation, when we don't > increase the HPET_T1_CMP register high enough. > > The result - timer stops ticking, since HPET_T1_CMP becomes less, > than the COUNTER and never increased again. > > The solution is (based on Linus's suggestion) to compare 64-bits > (on 64-bit x86), but to do the comparison on 32-bit signed > integers. > > Reported-by: Kirill Korotaev <dev@openvz.org> > Signed-off-by: Pavel Emelyanov <xemul@openvz.org> > Signed-off-by: Ingo Molnar <mingo@elte.hu> > --- > arch/x86/kernel/hpet.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c > index 64d5ad0..c761f91 100644 > --- a/arch/x86/kernel/hpet.c > +++ b/arch/x86/kernel/hpet.c > @@ -1075,7 +1075,7 @@ static void hpet_rtc_timer_reinit(void) > hpet_t1_cmp += delta; > hpet_writel(hpet_t1_cmp, HPET_T1_CMP); > lost_ints++; > - } while ((long)(hpet_readl(HPET_COUNTER) - hpet_t1_cmp) > 0); > + } while ((s32)(hpet_readl(HPET_COUNTER) - hpet_t1_cmp) > 0); > > if (lost_ints) { > if (hpet_rtc_flags & RTC_PIE)
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