RE: kupdated high load with heavy disk I/O

From: Rechenberg, Andrew (ARechenberg@shermanfinancialgroup.com)
Date: Mon Nov 26 2001 - 10:08:27 EST


Ken,

The 2.4.15pre7 kernel seems to have fixed my issue with kupdated and 4GB
RAM. We did some testing over the weekend and the box was still interactive
with a load of 7+. There still seems to be a lot of swapping going on
though. I've read from previous threads that 2.4 uses swap more readily
than 2.2 did, but should it use 10% of my swap and have almost 8MB
SwapCached?

Here are some numbers for example:

[root@mybox ~]# cat /proc/meminfo
        total: used: free: shared: buffers: cached:
Mem: 4092899328 4082126848 10772480 0 12406784 3672317952
Swap: 542826496 57561088 485265408
MemTotal: 3996972 kB
MemFree: 10520 kB
MemShared: 0 kB
Buffers: 12116 kB
Cached: 3578108 kB
SwapCached: 8140 kB
Active: 2964668 kB
Inactive: 877168 kB
HighTotal: 3145720 kB
HighFree: 2084 kB
LowTotal: 851252 kB
LowFree: 8436 kB
SwapTotal: 530104 kB
SwapFree: 473892 kB
[root@mybox ~]# free
             total used free shared buffers cached
Mem: 3996972 3986640 10332 0 12156 3577900
-/+ buffers/cache: 396584 3600388
Swap: 530104 56340 473764

The above question is more for my personal knowledge, but I would like to
know.

Thanks again for your help.

Regards,
Andy.

-----Original Message-----
From: Ken Brownfield [mailto:brownfld@irridia.com]
Sent: Wednesday, November 21, 2001 12:07 PM
To: Rechenberg, Andrew
Subject: Re: kupdated high load with heavy disk I/O

Yeah, the kswapd/kupdated issue was patched in -pre7:

         - me: modified Andrea VM page allocator tuning

-pre8 came out after I mailed you. ;-) So unless it's mentioned it
should stay in the kernel.

Of course, it's important to give it a try soon if you can, just to make
sure that it _does_ solve your specific problem. Especially before the
kernel is handed off to Marcelo.

Thx,

-- 
Ken.

On Wed, Nov 21, 2001 at 11:09:17AM -0500, Rechenberg, Andrew wrote: | Ken, | | Thanks for the reply. I would assume then that any future 15-pre kernel | would have the same fix? I ask because pre8 is now the current 15-pre. | | Thanks, | Andy. | | -----Original Message----- | From: Ken Brownfield [mailto:brownfld@irridia.com] | Sent: Tuesday, November 20, 2001 6:09 PM | To: Rechenberg, Andrew | Subject: Re: kupdated high load with heavy disk I/O | | | Be sure to tru 2.4.15-pre7 which should fix your problem. | -- | Ken. | brownfld@irridia.com | | On Tue, Nov 20, 2001 at 05:58:44PM -0500, Rechenberg, Andrew wrote: | | I have to find time to down the box because it's production, but as soon | as | | I do I'll post the numbers here. | | | | Thanks for your help. | | | | Regards, | | Andy. | | | | | | > Could you please guys try to reproduce the problem with kernel profiling | | > turned on and send us the output of readprofile? | | | | > This way we can know which function is using more CPU time, thus we can | | > identify the problem. | | | | | | On Wed, 14 Nov 2001, John McCutchan wrote: | | | | > Hi, | | > | | > I also have the exact same behaviour when running mkisofs. During the | | > creation of the ISO the interactive feel is sluggish and after mkisofs | | > is complete the box is sluggish and appears to lock up. During | | > this sluggish period there is alot of disk activity. This is under | | > 2.4.14 | | > | | > John | | > On Wed, Nov 14, 2001 at 06:01:23PM -0500, Rechenberg, Andrew wrote: | | > > Hello, | | > > | | > > I have read some previous threads about kupdated consuming 99% of CPU | | under | | > > intense disk I/O in kernel 2.4.x on the archives of linux-kernel | (April | | > > 2001), and some issues about I/O problems on linux-mm, but have yet to | | find | | > > any suggestions or fixes. I am currently experiencing the same issue | | and | | > > was wondering if anyone has any thoughts or suggestions on the issue. | I | | am | | > > not subscribed to the list so would you please CC: me directly on any | | > > responses? I can also check out the archives at theaimsgroup.com if a | | CC: | | > > would not be appropriate. Thank you. | | > > | | > > The issue that I am having is that when there is a heavy amount a disk | | I/O, | | > > the box becomes slightly unresponsive and kupdated is using 99.9% in | | 'top.' | | > > Sometimes the box appears to totally lock up. If one waits several | | seconds | | > > to a couple of minutes the system appears to 'unlock' and runs | | sluggishly | | > > for a while. This cycle will repeat itself until the I/O subsides. | The | | > > memory usage goes up to the full capacity of the box and then about | 10MB | | of | | > > swap is used while this problem is occurring. Memory and swap does | not | | get | | > > relinquished afer the incident. | | > > | | > > The issue appears in kernel 2.4.14 compiled directly from source from | | > > kernel.org with no patches. These problems manifest themselves with | | only | | > > one user doing heavy disk I/O. The normal user load on the box can | run | | > > between 350-450 users so this behavior would be unacceptable because | the | | > > application that is being run is interactive. With 450 users, and the | | same | | > > process running on a 2.2.20 kernel the performance of the box is | great, | | with | | > > only a very slightly noticeable slow down. | | > > | | > > I am running the Informix database UniVerse version 9.6.2.4 on a 4 | | processor | | > > 700MHz Xeon Dell PowerEdge 6400. The disk subsystem is controlled by | a | | PERC | | > > 2/DC RAID card with 128MB on-board cache (megaraid driver compiled | | directly | | > > in to the kernel). Data array is on 5 36GB 10K Ultra160 disks in a | | RAID5 | | > > configuration. The box has 4GB RAM, but is only using 2GB due to the | | move | | > > back to the 2.2 kernel. The only kernel paramters that have been | | modified | | > > are in /proc/sys/kernel/sem. All filesystems are ext2. | | > > | | > > If you need any more detailed info, please let me know. Any help on | | this | | > > problem would be immensely appreciated. Thank you in advance. | | > > | | > > Regards, | | > > Andrew Rechenberg | | > > Network Team, Sherman Financial Group | | > > arechenberg@shermanfinancialgroup.com | | > > | | > > -- | | > > To unsubscribe, send a message with 'unsubscribe linux-mm' in | | > > the body to majordomo@kvack.org. For more info on Linux MM, | | > > see: http://www.linux-mm.org/ | | > > | | > -- | | > To unsubscribe, send a message with 'unsubscribe linux-mm' in | | > the body to majordomo@kvack.org. For more info on Linux MM, | | > see: http://www.linux-mm.org/ | | > | | | | -- | | To unsubscribe, send a message with 'unsubscribe linux-mm' in | | the body to majordomo@kvack.org. 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