On Wed, Apr 14, 2021 at 12:22:56PM +0100, Shameer Kolothum wrote: > Hi, > > This is an attempt to revive this series originally posted by > Julien Grall[1]. The main motive to work on this now is because > of the requirement to have Pinned KVM VMIDs and the RFC discussion > for the same basically suggested[2] to have a common/better vmid > allocator for KVM which this series provides. > > Major Changes from v3: > > -Changes related to Pinned ASID support. > -Changes to take care KPTI related bits reservation. > -Dropped support for 32 bit KVM. > -Rebase to 5.12-rc7 > > Individual patches have change history for any major changes > from v3. > > Tests were performed on a HiSilicon D06 platform and so far not observed > any regressions. > > For ASID allocation, > > Avg of 10 runs(hackbench -s 512 -l 200 -g 300 -f 25 -P), > 5.12-rc7: Time:18.8119 > 5.12-rc7+v4: Time: 18.459 > > ~1.8% improvement. > > For KVM VMID, > > The measurement was made with maxcpus set to 8 and with the > number of VMID limited to 4-bit. The test involves running > concurrently 40 guests with 2 vCPUs. Each guest will then > execute hackbench 5 times before exiting. > > The performance difference between the current algo and the > new one are(ag. of 10 runs): > - 1.9% less exit from the guest > - 0.7% faster > > For complete series, please see, > https://github.com/hisilicon/kernel-dev/tree/private-v5.12-rc7-asid-v4 > > Please take a look and let me know your feedback. Although I think aligning the two algorithms makes sense, I'm not completely sold on the need to abstract all this into a library and whether the additional indirection is justified. It would be great to compare this approach with one where portions of the code are duplicated into a separate VMID allocator. Have you tried that to see what it looks like? Doesn't need to be a proper patch set, but comparing the end result might help to evaluate the proposal here. Will _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
