From: "Alex Bennée" <alex.bennee@linaro.org>
To: Richard Henderson <rth@twiddle.net>
Cc: Pranith Kumar <bobby.prani@gmail.com>,
qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH] tcg/softmmu: Increase size of TLB caches
Date: Wed, 06 Sep 2017 09:55:15 +0100 [thread overview]
Message-ID: <87ingwmcjw.fsf@linaro.org> (raw)
In-Reply-To: <8ea5a586-4d19-82db-f4b7-058229dc4124@twiddle.net>
Richard Henderson <rth@twiddle.net> writes:
> On 09/05/2017 05:33 PM, Pranith Kumar wrote:
>>> This significantly degrades performance of alpha-softmmu.
>>> It spends about 25% of all cpu time in memset.
>>
>> What workload does it degrade for? I will try to reproduce and see
>> which memset is causing this.
>
> emerge --update --ask @world
>
> which is a lot of python, iirc.
>
> It is the tlb flush memset that is causing this.
> The tlb has grown from a few kB to 300kB with your patch.
Hmm I wonder if this is QEMU doing global flushes which could actually
be partial TLB flushes? emerge is quite a memory hog though so its
conceivable we are generating a lot of churn as it runs.
--
Alex Bennée
prev parent reply other threads:[~2017-09-06 8:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-29 17:23 [Qemu-devel] [PATCH] tcg/softmmu: Increase size of TLB caches Pranith Kumar
2017-08-29 17:40 ` Richard Henderson
2017-09-05 21:50 ` Richard Henderson
2017-09-06 0:33 ` Pranith Kumar
2017-09-06 8:26 ` Richard Henderson
2017-09-06 8:55 ` Alex Bennée [this message]
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