Re: [PATCH 0/6] Reduce compaction scanning and lock contention

Mel Gorman wrote:

quoted

I did manage to get a couple which were slightly worse, but nothing like as
bad as before. Here are the results:

# grep -F '[k]' report | head -8
    45.60%       qemu-kvm  [kernel.kallsyms]     [k] clear_page_c
    11.26%       qemu-kvm  [kernel.kallsyms]     [k] isolate_freepages_block
     3.21%       qemu-kvm  [kernel.kallsyms]     [k] _raw_spin_lock
     2.27%           ksmd  [kernel.kallsyms]     [k] memcmp
     2.02%        swapper  [kernel.kallsyms]     [k] default_idle
     1.58%       qemu-kvm  [kernel.kallsyms]     [k] svm_vcpu_run
     1.30%       qemu-kvm  [kernel.kallsyms]     [k] _raw_spin_lock_irqsave
     1.09%       qemu-kvm  [kernel.kallsyms]     [k] get_page_from_freelist

# grep -F '[k]' report | head -8
    61.29%       qemu-kvm  [kernel.kallsyms]     [k] clear_page_c
     4.52%       qemu-kvm  [kernel.kallsyms]     [k] _raw_spin_lock_irqsave
     2.64%       qemu-kvm  [kernel.kallsyms]     [k] copy_page_c
     1.61%        swapper  [kernel.kallsyms]     [k] default_idle
     1.57%       qemu-kvm  [kernel.kallsyms]     [k] _raw_spin_lock
     1.18%       qemu-kvm  [kernel.kallsyms]     [k] get_page_from_freelist
     1.18%       qemu-kvm  [kernel.kallsyms]     [k] isolate_freepages_block
     1.11%       qemu-kvm  [kernel.kallsyms]     [k] svm_vcpu_run

Were the boot times acceptable even when these slightly worse figures
were recorded?

Yes, they were 10-20% slower as you might expect from the traces, rather
than a factor slower.

Thank you for the detailed reporting and the testing, it's much
appreciated. I've already rebased the patches to Andrew's tree and tested
them overnight and the figures look good on my side. I'll update the
changelog and push them shortly.

Great. On my side, I'm delighted that senior kernel developers such as you,
Rik and Avi took our bug report seriously and helped fix it!

Thank you,

Richard.

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