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From: "Denis V. Lunev" <den@openvz.org>
Message-ID: <56E6D39A.1020801@openvz.org>
Date: Mon, 14 Mar 2016 18:07:06 +0300
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Subject: Re: [Qemu-devel] [PATCH 5/9] log: improve performance of qemu_log
 and qemu_log_mask if disabled
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>

On 03/14/2016 05:30 PM, Paolo Bonzini wrote:
>
> On 14/03/2016 12:21, Denis V. Lunev wrote:
>> The patch is intended to avoid to perform any operation including
>> calculation of log function arguments when the log is not enabled due to
>> various reasons.
>>
>> Functions qemu_log and qemu_log_mask are replaced with variadic macros.
>>
>> Format checking performed by compiler will not suffer by this patch. It
>> will be done inside in fprintf arguments checking.
> Have you encountered a place that was calling them so hard that it
> caused performance problem?  If so, the logging should probably be
> replaced by a tracepoint.
>
> Paolo
>

inline functions can have side-effects, i.e. the arguments of them
can be evaluated depending on the compiler. with this approach
we are sure that this will not happen, ever.

Den