Messages in this thread |  | | Subject | Re: [PATCH] Preemption Latency Measurement Tool | From | Robert Love <> | Date | 19 Sep 2001 22:38:19 -0400 |
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On Wed, 2001-09-19 at 22:23, safemode wrote: > Is it possible to run the 20 worsst latency thing without having the pre-empt > patch ? I'd like to see how things run without the preempt patch and which > ones are the slowest. The last time i used the pre-empt patch i had worse > audio performance than not. Perhaps that's because i use alsa.
No, it requires the preemption patch. It uses the preemption count code in figuring out when code returns. Besides, if you are non-preemption and UP, you don't have many locking primitives anyhow (no concurrency concerns there).
You honestly should not have _worse_ latency with the patch. Even if something was wrong, it should still be about the same. However, most people are reporting a many many times over reduction in latency.
Your point about using ALSA is one of the reasons I am interested in this patch. Most of the people reporting high-latencies remaining even after the patch used ALSA.
If you try preemption again, along with this patch, we can find out what is causing your problems.
If you just want to gauage how long it takes to execute code from A to B in the kernel, there are various benchmarking tools as well as Andrew Morton's excellent timepegs work.
-- Robert M. Love rml at ufl.edu rml at tech9.net
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