Re: 2.6.2-rc2 Interactivity problems with SMP + HT

[Bill Davidsen]

Catalin BOIE wrote:
> On Thu, 29 Jan 2004, Robert M. Hyatt wrote:
>
>
> > It might be some IDE disk I/O that results from flushing buffers or
> > whatever.  I don't see this on my SCSI boxes, but I have seen an IDE
> > box get sluggish at times due to I/O.
>
>
> It is possible.
> vmstat shows a lot of writes when this happen.
> Seems that even reads hangs.
> I remember tat I was in pine and I tried to save a small file (under 1k)
> and it took 5-7 seconds to do it.
>
>
> > On Thu, 29 Jan 2004, Nick Piggin
> > wrote:
> >
> >
> > > Catalin BOIE wrote:
> > >
> > >
> > > > Hello!
> > > >
> > > > First, thank you very much for the effort you put for Linux!
> > > >
> > > > I have a Intel motherboard with SATA (2 Maxtor disks).
> > > > CPUs: 2 x 2.4GHz PIV HT = 4 processors (2 virtual)
> > > > 1 GB RAM.
> > > >
> > > > Load: postgresql and apache. Very low load (3-4 clients).
> > > >
> > > > RAID: Yes, soft RAID1 between the 2 disks.
> > > >
> > > > I have times when the console freeze for 3-4 seconds!
> > > > 2.6.0-test11 had the same problem (maybe longer times).
> > > > 2.6.1-rc2 worked good in this respect but crashed after 2 days. :(
> > > > 2.6.2-rc2 is back with the delay.
> > > >
> > > > Do you know why this can happen?
> > >
> > > There haven't been many scheduler changes there recently so
> > > maybe its something else.
> > >
> > > But you could try the latest -mm kernels. They have some
> > > Hyperthreading work in them (you need to enable CONFIG_SCHED_SMT).

Another possible improvement might come from the recent ide changes 
posted here for evaluation. There was a change to not block all devices 
or even all devices on a cable if one device delayed. I believe it was 
if a command didn't finish as intended, but I don't have it handy since 
I sent it off for testing tomorrow on a system which may have that problem.

There's a good bit of work on hangs happening right now, so you could 
wait or dig up the patches and try them. I think they were by Davin 
McCall if memory serves.


--
bill davidsen <davidsen@xxxxxxx>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979
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