Messages in this thread | | | Date | Wed, 26 Aug 2009 13:16:21 +0300 | From | Avi Kivity <> | Subject | Re: AlacrityVM benchmark numbers updated |
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On 08/26/2009 04:01 AM, Gregory Haskins wrote: > We are pleased to announce the availability of the latest networking > benchmark numbers for AlacrityVM. We've made several tweaks to the > original v0.1 release to improve performance. The most notable is a > switch from get_user_pages to switch_mm+copy_[to/from]_user thanks to a > review suggestion from Michael Tsirkin (as well as his patch to > implement it). > > This change alone accounted for freeing up an additional 1.2Gbps, which > is over 25% improvement from v0.1. The previous numbers were 4560Gbps > before the change, and 5708Gbps after (for 1500mtu over 10GE). This > moves us ever closer to the goal of native performance under virtualization. >
Interesting, it's good to see that copy_*_user() works so well. Note that there's a possible optimization that goes in the opposite direction - keep using get_user_pages(), but use the dma engine API to perform the actual copy. I expect that it will only be a win when using tso to transfer full pages. Large pages may also help.
Copyless tx also wants get_user_pages(). It makes sense to check if switch_mm() + get_user_pages_fast() gives better performance than get_user_pages().
-- error compiling committee.c: too many arguments to function
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