Re: [PATCH 03/21] Remove use of signalfd in block-raw-posix.c

Anthony Liguori
2009-04-30T13:28:51Z

Avi Kivity wrote:
> Anthony Liguori wrote:
>> Avi Kivity wrote:
>>> Anthony Liguori wrote:
>>>> We don't use signalfd in upstream QEMU. Instead, we always emulate
>>>> it.
>>>>
>>>
>>> With an extra thread -> so an extra context switch.
>>
>> We don't use an extra thread. We just install a signal handler that
>> writes to a pipe. At best, the added overhead is that we get EINTRs
>> more often but this is something we already handle.
>
> Oh okay. But signal delivery is slow; for example the FPU needs to be
> reset.

Is it really justified to add all of this extra code (including signalfd
emulation) for something that probably isn't even measurable?

I like using wiz-bang features of Linux as much as the next guy, but I
think we're stretching to justify it here :-)

--
Regards,

Anthony Liguori