Messages in this thread | | | Date | Wed, 29 Aug 2012 13:16:01 +0800 | From | "zhenzhong.duan" <> | Subject | Re: [PATCH] Parallelize mtrr init between cpus |
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On 2012-08-08 11:53, H. Peter Anvin wrote: > On 08/07/2012 07:08 PM, zhenzhong.duan wrote: >> >> >> 2012-08-08 00:32, H. Peter Anvin wrote: >>> On 08/07/2012 12:29 AM, zhenzhong.duan wrote: >>>> Current code serialize mtrr init with set_atomicity_lock. >>>> Mtrr init is quite slow when we bootup on a hvm with large mem, vcpus >>>> and pci passthroughed devices(eg. 24 vcpus + 90G mem). >>>> It took about ~30 mins to bootup, after patch, it took ~2 min. >>> When you're saying "HVM" do you mean "Xen HVM"? How does it behave on >>> native hardware? >>> >>> -hpa >> Yes, I mean Xen HVM. Bootup at same speed as before on baremetal. > > Then I would like to know why Xen HVM takes so infernally long. It > isn't a good idea to make gratuitous changes in the main kernel to > work around defects in Xen. > > -hpa Hi, Sorrry for late response, I have an opportunity to test the patch on an old G5 with 128 physical CPUS and 1 TB of memory. Arround 0.82 second time saved. Depends on cpu count on the system. I'm curious what's the usage of set_atomicity_lock here? There may be something I missed. thanks
Before patch: [ 13.176038] NMI watchdog enabled, takes one hw-pmu counter. [ 13.176444] Brought up 128 CPUs [ 13.176688] Total of 128 processors activated (578760.49 BogoMIPS). [ 14.035223] devtmpfs: initialized [ 17.277652] PM: Registering ACPI NVS region at 7f76e000 (401408 bytes) [ 17.279541] print_constraints: dummy: [ 17.280576] NET: Registered protocol family 16 After patch: [ 13.094227] smpboot cpu 127: start_ip = 90000 [ 13.185142] NMI watchdog enabled, takes one hw-pmu counter. [ 13.185599] Brought up 128 CPUs [ 13.185851] Total of 128 processors activated (578871.80 BogoMIPS). [ 13.224783] devtmpfs: initialized [ 16.468002] PM: Registering ACPI NVS region at 7f76e000 (401408 bytes) [ 16.469706] print_constraints: dummy: [ 16.470745] NET: Registered protocol family 16
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