[CentOS] Kernel update = slower ?
Sam Drinkard
sam at wa4phy.net
Sun Jun 4 13:57:05 UTC 2006
William L. Maltby wrote:
>On Thu, 2006-06-01 at 19:18 -0400, Sam Drinkard wrote:
>
>
>>Johnny,
>>
>> After reading about the VM issue, I concur. The previous kernel did
>>exhibit the behavior noted in the URL you sent. Looking right now, I
>>see a considerable difference in use / swap. The software running on
>>the machine generally uses anwhere from 1.2 > 1.4Gb of memory, and I had
>>noticed swap would, over time, increase, while there was still *some*
>>memory available, but it never would use totally all of it. The
>>application running right now is a little different from the one that
>>runs late-night and after 16z, so I'll take a peek at it either tonight
>>if I'm up or in the a.m. after the thing starts. I'll also note swap
>>and its size as time progresses to see if it increases as before with
>>free mem.
>>
>>
>
>I forget the start of this thread... was 64 bit only? Anyway, I had my
>32bit lock a couple times with symptoms like Sam mentions. Lots of swap
>used and no reason for it. Was using lots of open browsers, a couple
>different GUI MUAs, etc.
>
>Turned off things I didn't need for this workstation behind firewall on
>cable, like sendmail, spamc/d (started by evolution as it needs
>regardless of system started), etc.
>
>A *biggie*, maybe, is the stupid readahead and readahead_early stuff.
>Take a look at their file lists. Some small % suits your needs, the rest
>is just someone's idea of every possible thing that might speed up
>initial response. I completely disable these and have seen no
>difference. As I expected, after initial boot, most of it is wasted and
>the "non-manual" memory management does a better job than someone who
>probably got told "Make our boot faster than Windoze".
>
>Up now for 6 days running similar load (I think, haven't bothered to
>really measure it) and swap use is still good and response is still
>good.
>
>I suspect the heavy duty servers a lot of you have can also live without
>these readahead* things. Put a stopwatch on it and see. YMMV.
>
>
>
After uptime of a little over 3 days now, I'm not seeing any increase in
swap as I did prior, but then again, I don't exactly recall how long it
took before swap started increasing. One thing I do notice is for some
reason, the applications that nomally would consume between 1.2 - 1.4G
of memory is now down to 1.1 - 1.2, and swap is only lightly touched at
181mb. Don't know if this is due to the kernal update or what, but it
would seem logical that it is, since I see different behavior than
previously. I've not turned off readahead or readahead_early yet, but
will do so shortly and see if I can tell any difference in model run
times which did increase after the kernel update. One thing at a time I
guess :-)
Sam
--
Sam W.Drinkard -- sam at wa4phy.net
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