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Re: [Qemu-trivial] [PATCH] qemu-timer: remove unnecessary code

From: Cao jin
Subject: Re: [Qemu-trivial] [PATCH] qemu-timer: remove unnecessary code
Date: Wed, 13 Jul 2016 20:13:35 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0

On 07/13/2016 07:40 PM, Paolo Bonzini wrote:

On 13/07/2016 13:40, Cao jin wrote:

On 07/13/2016 06:21 PM, Paolo Bonzini wrote:

On 13/07/2016 11:06, Cao jin wrote:
When passed argument 'ns' is 0, macro DIV_ROUND_UP will return 0 also.

It's potentially slower though.

Is it because the function in the i/o loop path, so the potentially
extra arithmetical instructions matters?

It is quite common for ns to be zero, for example if a bottom half has
to be invoked.

I see. I need dig deeper to understand the wholely I/O mechanism. Thanks Paolo!

However, qemu_timeout_ns_to_ms is not used in the really important path
(which is aio_poll in aio-posix.c) so I guess your patch is okay.



Yours Sincerely,

Cao jin

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