Re: [linux-audio-dev] (not so low) low latency - acpi, dri, proc
Fernando Pablo Lopez-Lezcano wrote: I suspect acpi might be the culprit but I cannot try to disable it because on this particular laptop you need acpi to make sound work (probably something to do with routing of interrupts,, also tried pci=biosirq on a non-acpi kernel without success). Any suggestions? Hmmh, are you confusing ACPI and APIC here? ACPI is about power saving and APIC is about routing interrupts, etc... Proc: something has changed from the 2.4.18 to the 2.4.19 kernels (maybe the acpi proc interface is to blame?). Big mess of latency spikes in the proc latency test. No problems here with 2.4.19-jl series... Steady at 0.9 ms when using 128 byte buffers with ENS1371. - Jussi Laako -- PGP key fingerprint: 161D 6FED 6A92 39E2 EB5B 39DD A4DE 63EB C216 1E4B Available at PGP keyservers
Re: [linux-audio-dev] (not so low) low latency - acpi, dri, proc
Joern Nettingsmeier wrote: as a related note, i have found the soft-raid driver to cause higher latencies. when i do latencytest on a single scsi drive, i'm always 3ms, on the raid, i sometimes see 10. kernel is 2.4.20-pre2-ll. this data is as i recall it. if folks are interested, i'll make the graphs available. I think software raid driver needs some work to lower it's latency. Current -ll patch doesn't include anything for it, if I remember correctly. - Jussi Laako -- PGP key fingerprint: 161D 6FED 6A92 39E2 EB5B 39DD A4DE 63EB C216 1E4B Available at PGP keyservers
Re: [linux-audio-dev] (not so low) low latency - acpi, dri, proc
I suspect acpi might be the culprit but I cannot try to disable it because on this particular laptop you need acpi to make sound work (probably something to do with routing of interrupts,, also tried pci=biosirq on a non-acpi kernel without success). Any suggestions? Hmmh, are you confusing ACPI and APIC here? ACPI is about power saving and APIC is about routing interrupts, etc... I'm talking about the power saving subsystem. A kernel without the latest sourceforge acpi patch boots, but the routing of interrupts (and maybe something else?) is broken and sound does not work at all. With the acpi patch sound works fine, except for the 170mSec spikes I see when running latencytest. Obviously I cannot remove acpi to see if that is actually the problem :-) Proc: something has changed from the 2.4.18 to the 2.4.19 kernels (maybe the acpi proc interface is to blame?). Big mess of latency spikes in the proc latency test. No problems here with 2.4.19-jl series... Steady at 0.9 ms when using 128 byte buffers with ENS1371. Sigh... :-) -- Fernando
[linux-audio-dev] (not so low) low latency - acpi, dri, proc
Hi... anybody out there testing latency on an ACPI patched kernel? I have two kernels I'm testing: 2.4.19-x: 2.4.19 2.4.20-pre4 low latency for 2.4.19 (w/a couple of tweaks to patch pre4) acpi-20020815 for 2.4.20-pre4 2.4.18-x: 2.4.18 low latency for 2.4.18-pre10 acpi-20020726 for 2.4.18 On both 2.4.18-x and 2.4.19-x I get quite high periodic latency peaks that hover around 170mSecs. I suspect acpi might be the culprit but I cannot try to disable it because on this particular laptop you need acpi to make sound work (probably something to do with routing of interrupts,, also tried pci=biosirq on a non-acpi kernel without success). Any suggestions? DRI: I was about to write something about this and then checked and yes, the latest lowlat patch (for 2.4.19) is missing the dri reschedules (from Jussi Lako's patch set) so that DRI is unusable if you don't add them (at least on a Radeon based laptop). I'm recompiling with them to do more tests. Proc: something has changed from the 2.4.18 to the 2.4.19 kernels (maybe the acpi proc interface is to blame?). Big mess of latency spikes in the proc latency test. I'll post latency graphs later... this is all using latencytest 0.42 -- Fernando
