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. 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----- From: owner-informix-list@iiug.iiug.org [mailto:owner-informix-list@iiug.iiug.org]On Behalf Of Christian Knappke Sent: Friday, February 02, 2001 11:38 AM To: informix-list@iiug.org Subject: Re: LRU's and CLEANERS (IDS 9.21FC1) "Dirk Moolman" <dirkm@reach.co.za> wrote in message news:95dohr$onl$1@news.xmission.com... > > 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>

In article <95efd3$2ha$1@news.xmission.com>, Dirk Moolman <dirkm@reach.co.za> writes > >Thanks for the input Christian. I just still have to be convinced about >this one. I think your suggestion is also in line with what the manual >says, however I've heard of a lot of people having 128 LRUS on only a >couple of cpus. In a previous post by Art Kagel (Wed 11/29/2000 6:19 PM), >he mentioned that when you experience bufwaits (onstat -p), you should up >the LRUS. > >If I follow the manual, I will have to decrease my LRUS, if I follow Art's >advice, I will have to increase my LRUS. I think I'll try to increase them >for now and then take it from there. > Increase! Monitor the effect with onstat -g spi with only 8 lRUS you should find that the second column becomes very high for lru-?? entries! >Thanks again >Dirk >Reach Technologies > > >"People demand freedom of speech as a compensation for the freedom of >thought which they seldom use." >- Kierkegaard > > >-----Original Message----- >From: owner-informix-list@iiug.iiug.org >[mailto:owner-informix-list@iiug.iiug.org]On Behalf Of Christian Knappke >Sent: Friday, February 02, 2001 11:38 AM >To: informix-list@iiug.org >Subject: Re: LRU's and CLEANERS (IDS 9.21FC1) > > >"Dirk Moolman" <dirkm@reach.co.za> wrote in message >news:95dohr$onl$1@news.xmission.com... >> >> 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