Re: [Xen-devel] [PATCH V6] Switch from select() to poll() in xenconsoled's IO loop

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-01-09 at 09:50 +0000, Wei Liu wrote:
> In Linux select() typically supports up to 1024 file descriptors. This can be
> a problem when user tries to boot up many guests. Switching to poll() has
> minimum impact on existing code and has better scalibility.
> 
> pollfd array is dynamically allocated / reallocated. If the array fails to
> expand, we just ignore the incoming fd.
> 
> Change from V2:
>   * remove unnecessary malloc in initialize_pollfd_arrays
>   * use ROUND_UP to get new size of arrays
> 
> Change from V3:
>   * remove initialize and destroy function for array
>   * embedded tracking structure in struct domain, eliminate fd_to_pollfd
> 
> Change from V4:
>   * make xs_pollfd local to io.c
>   * add back the 5 ms fuzz
>   * handle POLLERR and POLLHUP
>   * treat POLLPRI as error if set in revents
>   * abort if xenconsoled's own fds get screwed
>   * handle broken tty if tty's fds get screwed
> 
> Change from V5:
>   * make some handles local to handle_io

The code now resets some of these to -1/NULL on exit from handle_io,
which isn't really necessary but I'm not to bothered about that.

>   * remove redundant xc interface
> 
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>



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