by
Sent: Saturday, February 03, 2001 4:39 PM
Subject: Re: FW: LRU's and CLEANERS (IDS 9.21FC1)
>Thanks for the input Christian. I just still have to be convinced about
>this one. I think your suggestion is also in line with what the manual
>says, however I've heard of a lot of people having 128 LRUS on only a
>couple of cpus. In a previous post by Art Kagel (Wed 11/29/2000 6:19 PM),
>he mentioned that when you experience bufwaits (onstat -p), you should up
>the LRUS.
>If I follow the manual, I will have to decrease my LRUS, if I follow Art's
>advice, I will have to increase my LRUS. I think I'll try to increase them
>for now and then take it from there.
> Increase! Monitor the effect with onstat -g spi
> with only 8 lRUS you should find that the second column becomes
> very high for lru-?? entries!
Thank you David, just one more question, what would be considered a high
value under
"onstat -g spi" for the lru-entries ?
Here is a sample of ours -
Num Waits Num Loops Avg Loop/Wait Name
6869 258573 37.64 fast mutex, lru-0
311 22370 71.93 fast mutex, lru-1
6599 244812 37.10 fast mutex, lru-2
334 21092 63.15 fast mutex, lru-3
6686 239281 35.79 fast mutex, lru-4
278 24724 88.94 fast mutex, lru-5
6415 205450 32.03 fast mutex, lru-6
347 28934 83.38 fast mutex, lru-7
>Thanks again
>Dirk
>Reach Technologies
>"People demand freedom of speech as a compensation for the freedom of
>thought which they seldom use."
>- Kierkegaard
>-----Original Message-----
>Sent: Friday, February 02, 2001 11:38 AM
>Subject: Re: LRU's and CLEANERS (IDS 9.21FC1)
>> The manual says the following about LRU's and CLEANERS
>> To monitor the percentage of dirty pages in LRU queues, use the
>onstat -R
>> command. When the number of dirty pages consistently exceeds the
>> LRU_MAX_DIRTY limit, you have too few LRU queues or too few page
>> cleaners. First, use the LRUS parameter to increase the number of
>LRU
>> queues.
>> If the percentage of dirty pages still exceeds LRU_MAX_DIRTY, use
>the
>> CLEANERS parameter to increase the number of page cleaners.
>> My parameters have the following values -
>> LRU_MAX_DIRTY 2
>> LRU_MIN_DIRTY 1
>> LRUS 30
>> CLEANERS 30
>> onstat -R gives me
>> 8587 dirty, 498979 queued, 500000 total, 524288 hash buckets, 2048
>buffer
>> size
>> start clean at 2% (of pair total) dirty, or 333 buffs dirty, stop at
>1%
>> 0 priority downgrades, 0 priority upgrades
>> According to what the manual says above, I need to increase my LRU's
>and
>> CLEANERS. Is it still true if max & min dirty is set to 2 & 1
>respectively
>> ? To make a long story short, how many LRU's and CLEANERS do I need
>?
>At SAP we recommend to configure LRUS and CLEANERS after NUMCPUVPS:
> LRUS = max( 4, NUMCPUVPS + 2 )
> CLEANERS = LRUS + 2
>After our experience we find performance advantages over the
>"traditional" settings, especially with low LRU_MAX/MIN_DIRTY setting
>and KAIO.
>HTH
>Christian
>--
>#include <std_disclaimer.h>
--
David Williams