disk IO request queue 2005-08-05 - By Magnus Andersen
Back
A few more questions...
1. What does you /etc/fstab look like?
2. What does the output from a cat of /proc/sys/vm/pagecache look like?
3. What does the output from a cat of /proc/meminfo look like?
4. Is kswapd/kscand processes running alot?
I don't think there is a big difference between hugetlb and bigpages.
I do know that I didn't have this implemented and I saw similar
behavior. Since I implemented hugetlb my server has been running
perfect. I also did not have a memory issue, but tuning the pagecache
and bdflush vm parameters help my performance alot. Also, are you
using AIO?
Magnus
On 8/5/05, nasvel <nasvel@(protected)> wrote:
> Magnus Andersen wrote:
>
> >This sounds very similar to what I experienced when I went live on a
> >RHEL 3 / 9i environment. A couple of questions.
> >
> >1. How are the Oracle share mounted to the system?
> >
> >
> For oracle, we've got 4 harddisk attached to a controller SCSI. We have
> a big tablespace which is composed of 16 dbf files. And the 16 files is
> spreading out on the first 3 disks, and the last disk we use to store
> the index tablespace.
>
> >2. Have you played with Linux vm?
> >
> >
> We've tuned the shmmax and max open files. And we're not lack of memory,
> there is 6G cached memory.
> [mrtg@(protected) mrtg]$ free
> total used free shared buffers cached
> Mem: 16167632 16105196 62436 0 189340 6684672
> -/+ buffers/cache: 9231184 6936448
> Swap: 4194160 1196604 2997556
>
> >3. Are you using hugetlb?
> >
> >
> no, because hugetlb is not available in AS2.1. But in AS2.1 the bigpages
> is enabled. According oracle, there is no big diff between them. You
> think it's important?
>
> http://www.oracle.com/technology/pub/notes/technote_rhel3.html
>
> Enterprise Linux 3 has replaced bigpages with a feature called hugetlb,
> a backport of what is also in Linux kernel 2.6. There are a few
> differences in how hugetlb works. Hugetlb behavior is similar to that of
> bigpages; the pages are backed by large TLB entries, are not pageable,
> and are preallocated, which means that once you allocate x megabytes of
> hugetlb pages, that amount of physical memory can be used only through
> hugetlbfs or shm allocated with SHM_HUGETLB.
>
> Thank you very much!
>
>
> dux
>
> >On 8/5/05, nasvel <nasvel@(protected)> wrote:
> >
> >
> >>Hi,
> >>
> >>since some weeks our database server (redhat taroon + oracle 9i)
> >>suffered from a very bad performance. The load avg climbed sometimes to
> >>80% :(, althought I think I've a powerful machine (HP, 3 Intel Xeon with
> >>16G memory).
> >>
> >>To try to find out the problem, I looked at the iostat report. I found
> >>the await time are pretty high, and the average queue length is about
> >>10. Someone told me that it is normal for a DB server, but I have some
> >>doubt, so I would like to have you guy's opinions about that...
> >>
> >>any suggestion is welcome, thanks
> >>
> >>dux
> >>
> >>=== begin output ===
> >>
> >> Linux 2.4.9-e.62enterprise 05.08.2005
> >>
> >>cpu-moy: %user %nice %sys %idle
> >> 17,63 0,02 12,31 70,04
> >>
> >>Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz
> >>await svctm %util
> >>cciss/c1d1p1
> >> 889,26 11,04 515,44 13,11 623,61 193,26 1,55 10,62
> >>21,30 8,03 42,42
> >>cciss/c1d0p1
> >> 273,76 45,13 100,64 48,85 872,20 751,95 10,86 10,62
> >>114,52 26,39 39,45
> >>cciss/c1d2p1
> >> 198,26 108,73 107,90 27,83 326,31 1061,51 10,22 10,62
> >>100,75 26,34 35,76
> >>cciss/c1d3p1
> >> 233,38 29,04 89,97 30,70 463,79 477,95 7,80 8,29
> >>68,69 26,78 32,32
> >>
> >>=== end output ===
> >>
> >>--
> >>Taroon-list mailing list
> >>Taroon-list@(protected)
> >>http://www.redhat.com/mailman/listinfo/taroon-list
> >>
> >>
> >>
> >
> >
> >
> >
>
> --
> Taroon-list mailing list
> Taroon-list@(protected)
> http://www.redhat.com/mailman/listinfo/taroon-list
>
--
Magnus Andersen
Systems Administrator / Oracle DBA
Walker & Associates, Inc.
--
Taroon-list mailing list
Taroon-list@(protected)
http://www.redhat.com/mailman/listinfo/taroon-list
Earn $52 per hosting referral at Lunarpages.
|
|
