[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] Singleshot timer firing late

  • To: "xen-devel@xxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxx>
  • From: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
  • Date: Mon, 19 May 2014 10:42:01 +0000
  • Accept-language: en-US
  • Delivery-date: Mon, 19 May 2014 10:44:29 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>
  • Thread-index: AQHPc073CxLCH++ABEuGMVku0l8l0Q==
  • Thread-topic: Singleshot timer firing late


While investigating a separate timer issue, I noticed that, in the
absence of other timers/factors, singleshot timers in Xen always fire
50us late (the timer slop amount).

From what I can see, this behavior was introduced by 116d62ddfd11
("timers: Simplify implementation logic.").  Before that, a similar
issue was fixed by 7e3e35eed67b ("Fix one timer range issue").

I have attached an RFC patch to program the timer to the nearest
deadline and then fire any timers up to 50us after that.  This is in
contrast with the previous behavior which would always program the
timer 50us after the nearest deadline.

Ross Lagerwall

Attachment: fix-late-timers.patch
Description: fix-late-timers.patch

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.