Re: 2.6.2-rc2 Interactivity problems with SMP + HT

[Bill Davidsen <davidsen@tmr.com>]

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@tmr.com>
   CTO TMR Associates, Inc
   Doing interesting things with small computers since 1979