[Bug 252728] Re: Jiffies too low for acceptable ppoll accuracy

2008-07-29 Thread janevert
The reporter is having expectations from the kernel which are not satisfied. In this case that (realttime) behavior is for a large part defined by the kernel configuration. And that has consciously been decided upon by the kernel team. As such not a bug. However, we do not need to let the report

[Bug 252728] Re: Jiffies too low for acceptable ppoll accuracy

2008-07-29 Thread janevert
Kay, With RHEL 1000Hz I would expect <1ms delays. So there's something funny as well. As for ppol using ns precision to specify the timeout is the future. Otherwise you end up changing the interface every 2 years (due to Moores law). As for your unique key, you could simply use the uptime. That

[Bug 252728] Re: Jiffies too low for acceptable ppoll accuracy

2008-07-29 Thread Kay Hayen
Hello, according the ps sources, the ELF note is the only reliable way to get the hands on the period one jiffy in /proc represents. The issue at hand is that I have implemented lock files that contain a "life" information from a process that is supposed to be unique, by combining the start time a

[Bug 252728] Re: Jiffies too low for acceptable ppoll accuracy

2008-07-29 Thread Kay Hayen
Hello, please find attached the output of dmesg from the Ubuntu machine. Please ignore the NVidia modules, this is only a recent change that I made, because xserver-xorg-driver-nv started to segfault too badly. The problem existed before. The only other noteworthy difference is that I am using the

[Bug 252728] Re: Jiffies too low for acceptable ppoll accuracy

2008-07-29 Thread Kay Hayen
Hello, please find attached the output of one of our RHEL machines with comparable hardware. We normally use HP G5 machines, but that is a normal desktop PC with Dual Core too. The claim is that the problem shows relatively hardware independent. I must admit, that we never use the same hardware wi

[Bug 252728] Re: Jiffies too low for acceptable ppoll accuracy

2008-07-29 Thread janevert
Umm, should've been more clear perhaps... Grep for PREEMPT on the ubuntu and redhat kernel configurations (usually located in /boot/config*). Also of interest are then the various HZ related config items (hint grep HZ /boot/config-..). And a diff between the redhat dmesg and ubuntu dmesg could a

[Bug 252728] Re: Jiffies too low for acceptable ppoll accuracy

2008-07-29 Thread janevert
Hi Kay, There are a couple of things you could check and/or add here as you provide very little information. First of all, your kernel, -4, is relatively old. At the moment -16 is the released kernel and -19 is the latest security update. Could you please test with that one? Could you please add