From: Andi Kleen <ak@linux.intel.com>
To: Joel Fernandes <joelaf@lab126.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, tj@kernel.org,
linux-rt-users@vger.kernel.org, Nick Piggin <npiggin@suse.de>
Subject: Re: [RFC] high preempt off latency in vfree path
Date: Tue, 22 Mar 2016 19:44:02 -0700 [thread overview]
Message-ID: <20160323024402.GA27856@tassilo.jf.intel.com> (raw)
In-Reply-To: <56F1F4A6.2060400@lab126.com>
> (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.
-Andi
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <ak@linux.intel.com>
To: Joel Fernandes <joelaf@lab126.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, tj@kernel.org,
linux-rt-users@vger.kernel.org, Nick Piggin <npiggin@suse.de>
Subject: Re: [RFC] high preempt off latency in vfree path
Date: Tue, 22 Mar 2016 19:44:02 -0700 [thread overview]
Message-ID: <20160323024402.GA27856@tassilo.jf.intel.com> (raw)
In-Reply-To: <56F1F4A6.2060400@lab126.com>
> (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.
-Andi
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next prev parent reply other threads:[~2016-03-23 2:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-23 1:43 [RFC] high preempt off latency in vfree path Joel Fernandes
2016-03-23 1:43 ` Joel Fernandes
2016-03-23 1:43 ` Joel Fernandes
2016-03-23 2:44 ` Andi Kleen [this message]
2016-03-23 2:44 ` Andi Kleen
2016-03-23 19:03 ` Joel Fernandes
2016-03-23 19:03 ` Joel Fernandes
2016-03-23 19:03 ` Joel Fernandes
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