Re: [Qemu-devel] [5578] Increase default IO timeout from 10ms to 5s

[Anthony Liguori <anthony@codemonkey.ws>]

If anyone notices a slow down, I'd check this revision.  There may be 
broken bits of code out there that depends on wake up rate.  I've done a 
fair bit of testing and haven't found any but you never know.

Regards,

Anthony Liguori

Anthony Liguori wrote:
> Revision: 5578
>           http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5578
> Author:   aliguori
> Date:     2008-10-31 18:40:25 +0000 (Fri, 31 Oct 2008)
>
> Log Message:
> -----------
> Increase default IO timeout from 10ms to 5s
>
> With the recent changes to the main loop, we no longer have unconditional
> polling.  This means we can now sleep in select() for much longer than we
> previously did.  This patch increases our select() sleep time from 10ms to 5s
> which is effectively unlimited since we're going to wake up sooner than that
> in almost all circumstances.
>
> With this patch, I see the number of wake-ups with an idle dynamic ticks guest
> drop from 80 per second to about 15 times per second.
>
> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
>
> Modified Paths:
> --------------
>     trunk/vl.c
>
> Modified: trunk/vl.c
> ===================================================================
> --- trunk/vl.c	2008-10-31 18:07:17 UTC (rev 5577)
> +++ trunk/vl.c	2008-10-31 18:40:25 UTC (rev 5578)
> @@ -8182,7 +8182,7 @@
>                              timeout = 0;
>                      }
>                  } else {
> -                    timeout = 10;
> +                    timeout = 5000;
>                  }
>              } else {
>                  timeout = 0;
> @@ -8192,7 +8192,7 @@
>                  ret = EXCP_INTERRUPT;
>                  break;
>              }
> -            timeout = 10;
> +            timeout = 5000;
>          }
>  #ifdef CONFIG_PROFILER
>          ti = profile_getclock();
>
>
>
>
>