Messages in this thread |  | | Date | Mon, 16 Jun 2008 22:04:46 +0530 | From | "Balbir Singh" <> | Subject | Re: [PATCH] Delay accounting, fix incorrect delay time when constantly waiting on runqueue |
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On Mon, Jun 16, 2008 at 3:11 PM, <bharathravi1@gmail.com> wrote: > From: Bharath Ravi <bharathravi1@gmail.com> > > This patch corrects the incorrect value of per process run-queue wait time > reported by delay statistics. The anomaly was due to the following reason. > When a process leaves the CPU and immediately starts waiting for CPU on > the runqueue (which means it remains in the TASK_RUNNABLE state), the time > of re-entry into the run-queue is never recorded. Due to this, the waiting time > on the runqueue from this point of re-entry upto the next time it hits the CPU > is not accounted for. This is solved by recording the time of re-entry of a > process leaving the CPU in the sched_info_depart() function IF the process will > go back to waiting on the run-queue. This IF condition is verified by checking > whether the process is still in the TASK_RUNNABLE state. > > The patch was tested on 2.6.26-rc6 using two simple CPU hog programs. The > values noted prior to the fix did not account for the time spent on the > runqueue waiting. After the fix, the correct values were reported back > to user space. > > Signed-off-by: Bharath Ravi <bharathravi1@gmail.com> > Signed-off-by: Madhava K R <madhavakr@gmail.com>
Looks very good to me
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Balbir
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