Re: [PATCH-v2 0/4] KVM: dirty logging optimization

[Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>]

(2010/11/22 14:40), Takuya Yoshikawa wrote:
> Hi,
>
> I updated my patch set with your comments reflected.

Changelog:
   - used enum
   - lpage_idx issues
   - function names
   - measurements


>
>   - [PATCH 1/4] KVM: fix race condition in kvm_mmu_slot_remove_write_access()
>   - [PATCH 2/4] KVM: introduce helper to access lpage_info
>   - [PATCH 3/4] KVM: count the number of dirty pages for each memslot
>   - [RFC PATCH 4/4] KVM: selective write protection using dirty bitmap
>
> The first one is a small fix and maybe worth applying seperately.
>
> The second and third are preparation for the last one, but I believe
> each has its own value.
>
>
> I measured the time consumed by kvm_mmu_slot_remove_write_access[_mask]()
> to decide at which conditions we choose *_mask(). Please check below!
>
>   * I implemented dirty_level_memslot() based on these results.
>     See [PATCH 4]
>
>
>
> Is it possible to apply [PATCH 1 and 2] first?
> It will help me a lot to concentrate on the main part.
>
>
>    Takuya
>
> ===
> Test
>
>   - On core 2 duo machine (without EPT)
>      =>  just because there was already test environment.
>   - 1GB RAM for the guest
>   - Workloads:
>     x11perf for frame buffer test
>     "find /" loop for live-migration test
>
>   - Time was measured by rdtscll
>     kvm mask: our method
>     kvm orig: original method
>
>
> a) Frame buffer
> ---------------------------------------------------------------
>
> kernel: [ 5584.954209] kvm: nr_dirty_pages/npages = 8/4096
> kernel: [ 5584.954240] kvm mask: time(tsc) = 9485
>
> kernel: [ 5992.185125] kvm: nr_dirty_pages/npages = 7/4096
> kernel: [ 5992.185389] kvm orig: time(tsc) = 444724
>
> 45 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5588.330585] kvm: nr_dirty_pages/npages = 80/4096
> kernel: [ 5588.330623] kvm mask: time(tsc) = 16688
>
> kernel: [ 5996.183982] kvm: nr_dirty_pages/npages = 80/4096
> kernel: [ 5996.184275] kvm orig: time(tsc) = 495551
>
> 30 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5578.156641] kvm: nr_dirty_pages/npages = 195/4096
> kernel: [ 5578.156690] kvm mask: time(tsc) = 27335
>
> kernel: [ 5985.109688] kvm: nr_dirty_pages/npages = 195/4096
> kernel: [ 5985.109820] kvm orig: time(tsc) = 194530
>
> 7 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5605.821017] kvm: nr_dirty_pages/npages = 375/4096
> kernel: [ 5605.821077] kvm mask: time(tsc) = 35049
>
> kernel: [ 6014.627767] kvm: nr_dirty_pages/npages = 375/4096
> kernel: [ 6014.628190] kvm orig: time(tsc) = 702737
>
> 20 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5573.551459] kvm: nr_dirty_pages/npages = 576/4096
> kernel: [ 5573.551532] kvm mask: time(tsc) = 46718
>
> kernel: [ 5981.486862] kvm: nr_dirty_pages/npages = 576/4096
> kernel: [ 5981.487036] kvm orig: time(tsc) = 210385
>
> 5 times faster
>
> ---------------------------------------------------------------
>
>
>
> b) Live-migration (1GB RAM)
> ---------------------------------------------------------------
>
> kernel: [ 5011.599573] kvm: nr_dirty_pages/npages = 52/261888
> kernel: [ 5011.599624] kvm mask: time(tsc) = 33712
>
> kernel: [ 4297.465401] kvm: nr_dirty_pages/npages = 50/261888
> kernel: [ 4297.465918] kvm orig: time(tsc) = 894593
>
> 25 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5009.045842] kvm: nr_dirty_pages/npages = 120/261888
> kernel: [ 5009.045940] kvm mask: time(tsc) = 50575
>
> kernel: [ 4295.438092] kvm: nr_dirty_pages/npages = 106/261888
> kernel: [ 4295.438427] kvm orig: time(tsc) = 525140
>
> 10 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5016.914031] kvm: nr_dirty_pages/npages = 251/261888
> kernel: [ 5016.914160] kvm mask: time(tsc) = 78750
>
> kernel: [ 4297.265937] kvm: nr_dirty_pages/npages = 260/261888
> kernel: [ 4297.266411] kvm orig: time(tsc) = 782446
>
> 10 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5015.717535] kvm: nr_dirty_pages/npages = 526/261888
> kernel: [ 5015.717697] kvm mask: time(tsc) = 130137
>
> kernel: [ 4295.370101] kvm: nr_dirty_pages/npages = 596/261888
> kernel: [ 4295.370589] kvm orig: time(tsc) = 644805
>
> 5 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5011.693010] kvm: nr_dirty_pages/npages = 1029/261888
> kernel: [ 5011.693177] kvm mask: time(tsc) = 219863
>
> kernel: [ 4295.760635] kvm: nr_dirty_pages/npages = 1025/261888
> kernel: [ 4295.761078] kvm orig: time(tsc) = 767333
>
> 3 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5014.805403] kvm: nr_dirty_pages/npages = 2219/261888
> kernel: [ 5014.805676] kvm mask: time(tsc) = 454314
>
> kernel: [ 4302.186712] kvm: nr_dirty_pages/npages = 1982/261888
> kernel: [ 4302.191418] kvm orig: time(tsc) = 2294187
>
> 5 times faster
>
> ---------------------------------------------------------------
>
> kernel: [ 5015.305794] kvm: nr_dirty_pages/npages = 4143/261888
> kernel: [ 5015.306291] kvm mask: time(tsc) = 847175
>
> kernel: [ 4302.068376] kvm: nr_dirty_pages/npages = 3835/261888
> kernel: [ 4302.069456] kvm orig: time(tsc) = 1855105
>
> 3 times faster
>
> ---------------------------------------------------------------
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