[linux-audio-user] 2.6.13 kernel: which patches for better latency
Eric Dantan Rzewnicki
rzewnickie at rfa.org
Tue Sep 13 16:45:19 EDT 2005
On Mon, Sep 12, 2005 at 03:39:14PM -0500, Reuben Martin wrote:
> On 9/12/05, Reuben Martin <reuben.m at gmail.com> wrote:
> > On 9/12/05, Eric Dantan Rzewnicki <rzewnickie at rfa.org> wrote:
> > > On Thu, Sep 08, 2005 at 08:38:02PM -0500, Reuben Martin wrote:
> > > > On 9/7/05, guy <sayhi2guy at tiscali.co.uk> wrote:
> > > For historical clarification ( and someone correct me if I'm wrong on
> > > any of this ), Ingo did a set of low latency patches for 2.2/2.4 that
> > > basically showed that breaking up long code pathes could improve linux's
> > > latency performance. These were proof of concept patches, in a sense,
> > > but not accepted, nor intended, for the mainline kernel.
> > > Andrew Morton created a smaller and more tightly focused set of
> > > long-code-path-splitting low-latency patches for 2.4 inspired by Ingo's
> > > earlier work. These were intended to find an approach to achieving
> > > low-latency more acceptable to the kernel devs.
> > > Robert Love created a set of Preemption patches for 2.4 that were
> > > commonly applied along with Andrew's LL patches. The preemption patches
> > > were a different approach to achieve low-latency which allowed code
> > > paths which might run for a long time to be marked as pre-emptible.
> > I know all three of them contributed. I'm not sure who's was merged
> > into 2.5. I remember I used to use a combination of two diffferent
> > latency patch sets.
Yeah. I think it was a combination of all of their efforts. Andrew
maintained the LL (low latency) patches and Robert maintained the PE
(pre-empt) though they and others may have contributed to either or both
I remember naming my kernels something like 2.4.19-pe-ll, or some such.
> > > Much of Andrew and Robert's work on 2.4 was incorporated into the 2.5
> > > development kernel and thus the 2.6 series. However there were still
> > > latency problems with 2.6, so Ingo has again taken the lead in producing
> > > the current series of realtime-preemption patches. A lot of this work is
> > > now present in the mainline 2.6.13.x kernel.
> > If I understand correctly, chunks of his patch are slowly absorbed
> > into the mainline a bit at a time while he continues to keep finding
> > ways to shorten the length of code paths.
That is also my understanding of Ingo's current patch set's adoption
into the mainline.
Eric Dantan Rzewnicki | Systems Administrator
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