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Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_op
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd. |
Date: |
Thu, 24 Jul 2008 09:31:25 +0100 |
User-agent: |
Mutt/1.4.1i |
On Thu, Jul 24, 2008 at 09:54:43AM +0200, Gerd Hoffmann wrote:
> Anthony Liguori wrote:
> > I really don't like introducing polling. I think we should be trying to
> > reduce the overall number of wake ups in QEMU, not add more.
>
> Right now qemu wakes up quite often anyway, so it doesn't become worse
> (bad excuse, I know).
>
> > I'm inclined to say that we simply declare that reconnecting to a PTY is
> > broken/unsupported and strongly encourage the use of something else
> > (like unix sockets). That's always been my understanding FWIW.
>
> It's not only reconnects, its also the initial connect.
>
> Right now qemu simply blocks once the pty output buffer is full. With
> nobody reading this effectively means qemu blocks forever and doesn't
> responds any more to anything. It can't stay that way IMO.
>
> I think we have three options here:
>
> (1) Detect whenever someone is connected. Drawback: needs polling
> (unless someone comes up with a better patch).
> (2) Run ptys in non-blocking mode. Drawback: we risk loosing data
> in case the pty reader is slow (also when nobody is connected of
> course, but that is intentional ...).
> (3) Drop pty support. Drawback: we break existing setups.
NACK to that last option - I'd rather keep existing blocking behaviour,
than break existing applications using PTYs.
Daniel.
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- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., (continued)
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Daniel P. Berrange, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Gerd Hoffmann, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Anthony Liguori, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Daniel P. Berrange, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Anthony Liguori, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Gerd Hoffmann, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Anthony Liguori, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Jamie Lokier, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Gerd Hoffmann, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Gerd Hoffmann, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd.,
Daniel P. Berrange <=
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Jamie Lokier, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Samuel Thibault, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Gerd Hoffmann, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Gerd Hoffmann, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Anthony Liguori, 2008/07/23
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Daniel P. Berrange, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Anthony Liguori, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Jamie Lokier, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Gerd Hoffmann, 2008/07/24
- Re: [Qemu-devel] [PATCH 2/3] Always use nonblocking mode for qemu_chr_open_fd., Paul Brook, 2008/07/24