Messages in this thread | | | Subject | Re: 2.6.15-rc5: latency regression vs 2.6.14 in exit_mmap->free_pgtables | From | Lee Revell <> | Date | Wed, 18 Jan 2006 20:42:39 -0500 |
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On Wed, 2005-12-28 at 22:59 +0000, Hugh Dickins wrote: > I'm to blame for that - sorry. It didn't occur to me that I was > moving any signficant amount of work (on mms with many vmas) into the > section with preemption disabled. Actually, the mm->page_table_lock > is _not_ held there any more; but preemption is still disabled while > using the per-cpu mmu_gathers. > > I wish you'd found it at -rc1 time. It's not something that can > be properly corrected in a hurry. The proper fix is to rework the > tlb_gather_mmu stuff, so it can be done without preemption disabled. > It's already a serious limitation in unmap_vmas, with CONFIG_PREEMPT's > ZAP_BLOCK_SIZE spoiling throughput with far too many TLB flushes. > > On my list to work on; but the TLB always needs great care, and this > goes down into architectural divergences, with truncation of a mapped > file adding further awkward constraints. I imagine 2.6.16-rc1 is only > a couple of weeks away, so it's unlikely to be fixed in 2.6.16 either. >
Hugh,
Is this believed to be fixed in 2.6.16-rc1?
Lee
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