[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff |
Date: |
Wed, 24 Jul 2013 09:54:57 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 |
Il 24/07/2013 09:43, liu ping fan ha scritto:
> Paid some time to dig the kernel code, and find out that the
> resolution lost by timeout of poll/select..etc is cause by the timeout
> is a slack region.
> See code in
> do_poll()
> if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
>
> Notice the slack param, it causes the lose of resolution.
> The process default slack time inherits from init_task and it is
> .timer_slack_ns = 50000, /* 50 usec default slack */
> But we can fix it by PR_SET_TIMERSLACK to decrease it for select/poll/...
Right, good catch. I just learnt about PR_SET_TIMERSLACK. :)
Alex, can you add it to your series? (Note that you must set a timer
slack of 1, because 0 is interpreted as "default").
> So ppoll with timerslack adjustment will meet our requirement. But
> what about other non-linux system?
They might have their own mechanism similar to PR_SET_TIMERSLACK.
Paolo
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, (continued)
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, liu ping fan, 2013/07/23
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Paolo Bonzini, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Alex Bligh, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Paolo Bonzini, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Alex Bligh, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Paolo Bonzini, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Alex Bligh, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Paolo Bonzini, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, liu ping fan, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, liu ping fan, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff,
Paolo Bonzini <=
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Alex Bligh, 2013/07/24
- [Qemu-devel] [PATCHv2a] [RFC 8/7 (really)] Add prctl(PR_SET_TIMERSLACK, 1, ...) to reduce timer slack, Alex Bligh, 2013/07/24
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Alex Bligh, 2013/07/23
- Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Stefan Hajnoczi, 2013/07/25
Re: [Qemu-devel] [RFC 0/8] arm AioContext with its own timer stuff, Stefan Hajnoczi, 2013/07/25