Re: [RFC] high preempt off latency in vfree path

From	Joel Fernandes <joelaf@lab126.com>
Newsgroups	linux.kernel
Subject	Re: [RFC] high preempt off latency in vfree path
Date	2016-03-23 20:10 +0100
Message-ID	<rfWkh-7VP-9@gated-at.bofh.it> (permalink)
References	<rfG5Q-4yd-9@gated-at.bofh.it> <rfH1T-5cz-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 03/22/16 19:44, Andi Kleen wrote:
>> (1)
>> One is we reduce the number of lazy_max_pages (right now its around 32MB per core worth of pages).
>>
>> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
>> index aa3891e..2720f4f 100644
>> --- a/mm/vmalloc.c
>> +++ b/mm/vmalloc.c
>> @@ -564,7 +564,7 @@ static unsigned long lazy_max_pages(void)
>>
>>          log = fls(num_online_cpus());
>>
>> -       return log * (32UL * 1024 * 1024 / PAGE_SIZE);
>> +       return log * (8UL * 1024 * 1024 / PAGE_SIZE);
>>   }
>
> This seems like the right fix to me.  Perhaps even make it somewhat smaller.
>
> Even on larger systems it's probably fine because they have a lot more
> cores/threads these days, so it will be still sufficiently large.
>

Thanks Andi. I'll post a patch then.

Regards,
Joel

> -Andi
>

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[RFC] high preempt off latency in vfree path Joel Fernandes <joelaf@lab126.com> - 2016-03-23 02:50 +0100
  Re: [RFC] high preempt off latency in vfree path Andi Kleen <ak@linux.intel.com> - 2016-03-23 03:50 +0100
    Re: [RFC] high preempt off latency in vfree path Joel Fernandes <joelaf@lab126.com> - 2016-03-23 20:10 +0100

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