On Monday 19 December 2005 02:22, Con Kolivas wrote: > On Monday 19 December 2005 02:19, Con Kolivas wrote: > > Here is yet another updated version of the dynticks code. > > > > Changes: > > > > Numerous cleanups, microoptimisations and locking improvements. > > > > One bugfix for the next tick accounting used in early_dyn_reprogram > > > > I've yet to find the cause for grossly high cpu accounting on SMP. I'd > > appreciate any help in this area as it's the last showstopper for this > > code. > > > > Obvious power savings are evident on uniprocessor now in on/off > > comparisons using pmstats. > > That would be dynticks-051218 I mean, sorry. Oops, wrong locking order may cause a livelock so this patch will be needed. Uploaded a 051218-1 patch to website with this bug fix. http://ck.kolivas.org/patches/dyn-ticks/ Cheers, Con --- arch/i386/kernel/dyn-tick.c | 7 +++---- 1 files changed, 3 insertions(+), 4 deletions(-) Index: linux-2.6.15-rc5-dt/arch/i386/kernel/dyn-tick.c =================================================================== --- linux-2.6.15-rc5-dt.orig/arch/i386/kernel/dyn-tick.c +++ linux-2.6.15-rc5-dt/arch/i386/kernel/dyn-tick.c @@ -126,16 +126,14 @@ static void do_dyn_tick_interrupt(struct { int cpu = smp_processor_id(); + write_seqlock(&xtime_lock); spin_lock(&dyn_tick->lock); if (cpus_equal(nohz_cpu_mask, cpu_online_map)) { /* All were sleeping, recover jiffies */ int lost = cur_timer->mark_offset(); - if (lost && in_irq()) { - write_seqlock(&xtime_lock); + if (lost && in_irq()) do_timer(regs); - write_sequnlock(&xtime_lock); - } if (dyntick_using_lapic()) { enable_pit_timer(); if (unlikely(lost > DYN_TICK_MAX_SKIP + 1)) @@ -145,6 +143,7 @@ static void do_dyn_tick_interrupt(struct } clear_nohz_cpu(cpu); spin_unlock(&dyn_tick->lock); + write_sequnlock(&xtime_lock); /* Make sure we don't miss the next timer tick */ dyn_early_reprogram(1);
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