On Thu, Jul 12, 2012 at 06:35:09PM +0900, Takuya Yoshikawa wrote: > On Thu, 5 Jul 2012 23:05:46 +0900 > Takuya Yoshikawa <takuya.yoshikawa@xxxxxxxxx> wrote: > > > On Thu, 5 Jul 2012 14:50:00 +0300 > > Gleb Natapov <gleb@xxxxxxxxxx> wrote: > > > > > > Note that "if (!nr_to_scan--)" check is removed since we do not try to > > > > free mmu pages from more than one VM. > > > > > > > IIRC this was proposed in the past that we should iterate over vm list > > > until freeing something eventually, but Avi was against it. I think the > > > probability of a VM with kvm->arch.n_used_mmu_pages == 0 is low, so > > > it looks OK to drop nr_to_scan to me. > > > > Since our batch size is 128, the minimum positive @nr_to_scan, it's almost > > impossible to see the effect of the check. > > Thinking more about this: > > I think freeing mmu pages by shrink_slab() is problematic. > > For example, if we do > # echo 2 /proc/sys/vm/drop_caches > on the host, some mmu pages will be freed. > > This is not what most people expect, probably. > > > Although this patch is needed to care about shadow paging's extreme > mmu page usage, we should do somthing better in the future. > > What I think reasonable is not treating all mmu pages as freeable: > - determine some base number of mmu pages: base_mmu_pages > - return (total_mmu_pages - base_mmu_pages) to the caller > > * We may use n_max_mmu_pages for calculating this base number. > > By doing so, we can avoid freeing mmu pages especially when EPT/NPT ON. Takuya, Can't understand, can you please expand more clearly? TIA -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
