Re: How much RAM is to much

From: kyle Hailey <kylelf_at_gmail.com>
Date: Wed, 20 Apr 2011 16:05:22 -0700
Message-ID: <BANLkTimtYFthR=t-nuxLEjftZ6cJDhxArw_at_mail.gmail.com>

What metrics tell you that filesystemio_options=directio "works even better then 'forcedirectio' option used on filesystem side." ?

On Solaris, I didn't notice any difference between filesystemio_options=directio and using forcedirectio on the mount. If either one of them was set my performance was similar.

Here are some response times for a full tablescan doing 56000 physical reads, and 87000 consistent reads, along with the vmstat

1)

---

mount=no-forcedirectio, filesystemio_options=setall

 kthr memory page disk faults cpu  r b w swap free re mf pi po fr de sr s0 s1 s2 -- in sy cs us sy id
 0 0 0 633904 2716200 0 0 0 0 0 0 0 0 5 0 0 8849 1879 7501 1 2 98
 0 0 0 633904 2716248 0 45 0 0 0 0 0 0 3 0 0 9031 2395 7610 1 2 97
 0 0 0 621472 2707176 214 806 0 0 0 0 0 1 4 0 0 8982 5888 7656 2 2 96
 0 0 0 612168 2699240 676 1690 0 0 0 0 0 1 3 0 0 9025 8534 7677 3 2 95
 0 0 0 612824 2699688 8 44 0 0 0 0 0 3 4 0 0 8314 2600 7045 1 1 98
 0 0 0 612824 2699752 0 1 0 0 0 0 0 10 9 0 0 8985 2226 7669 1 2 98
 0 0 0 612760 2699632 0 49 0 0 0 0 0 0 2 0 0 8549 2818 7293 1 2 97

Elapsed: 00:00:39.23
Elapsed: 00:00:20.24
Elapsed: 00:00:17.97
Elapsed: 00:00:17.91
Elapsed: 00:00:19.91
Elapsed: 00:00:19.31
Elapsed: 00:00:17.95

2)

---

mount=forcedirectio, filesystemio_options=none

 kthr memory page disk faults cpu  r b w swap free re mf pi po fr de sr s0 s1 s2 -- in sy cs us sy id
 0 0 0 586472 3093824 75 271 0 0 0 0 0 0 2 0 0 9129 2968 7841 1 2 97
 0 0 0 589744 3096920 0 28 0 0 0 0 0 1 851 0 0 9484 2373 8126 1 2 97
 0 0 0 589744 3096920 0 20 0 0 0 0 0 2 0 0 0 8923 2624 7664 1 2 97
 0 0 0 589744 3096928 0 44 0 0 0 0 0 3 2 0 0 9743 2912 8361 2 2 96
 0 0 0 589744 3097128 0 0 0 0 0 0 0 1 0 0 0 9582 2205 8218 1 2 97
 0 0 0 589744 3097136 453 1515 0 0 0 0 0 2 3 0 0 9631 9173 8190 2 2 96
 0 0 0 565584 3079304 528 1496 0 0 0 0 0 2 4 0 0 9999 8728 8713 2 2 95
 1 0 0 561096 3075384 331 717 0 0 0 0 0 2 1 0 0 9431 5682 8101 2 2 96

Elapsed: 00:00:42.04
Elapsed: 00:00:17.86
Elapsed: 00:00:19.16
Elapsed: 00:00:19.13
Elapsed: 00:00:18.04
Elapsed: 00:00:18.18
Elapsed: 00:00:16.18

3)

---

mount=forcedirectio, filesystemio_options=setall

 kthr memory page disk faults cpu  r b w swap free re mf pi po fr de sr s0 s1 s2 -- in sy cs us sy id
0 0 0 534656 3047352 17 10 0 0 0 0 0 1 1 0 0 8756 2335 7503 1 2 98
 0 0 0 534656 3047360 0 0 0 0 0 0 0 2 0 0 0 9673 2075 8332 1 2 97
 0 0 0 534656 3047360 0 28 0 0 0 0 0 0 2 0 0 9692 2345 8349 1 2 97
 0 0 0 534656 3047424 0 18 0 0 0 0 0 0 1 0 0 9105 2701 7811 2 2 97
 0 0 0 547728 3056896 0 44 0 0 0 0 0 2 0 0 0 9884 3113 8453 2 2 96
 0 0 0 546640 3055808 0 0 0 0 0 0 0 0 2 0 0 9253 2061 7906 1 2 97
 0 0 0 546640 3055808 0 1 0 0 0 0 0 4 1 0 0 9750 2146 8354 1 2 97
 0 0 0 546640 3055808 0 25 0 0 0 0 0 2 13 0 0 9670 2366 8261 1 2 97
 0 0 0 546640 3055808 0 17 0 0 0 0 0 1 8 0 0 9620 2794 8282 1 2 97
 0 0 0 547728 3056896 0 45 0 0 0 0 0 1 1 0 0 5529 2647 4820 1 1 98

Elapsed: 00:00:39.22
Elapsed: 00:00:19.03
Elapsed: 00:00:18.80
Elapsed: 00:00:18.29
Elapsed: 00:00:19.19
Elapsed: 00:00:17.99
Elapsed: 00:00:18.97

• Kyle

2011/4/20 <przemolicc_at_poczta.fm>

> On Tue, Apr 19, 2011 at 08:42:34PM +0200, D'Hooge Freek wrote:
> > Maybe it used to be necessary and no one has verified this on newer
> versions?
>
> We have been using directio setup on Oracle side for a few years.
> Since (I guess) 9g (just recently switched to 10g).
> It works even better then 'forcedirectio' option used on filesystem side.
>
>
> Regards
> Przemyslaw Bak (przemol)
> --
> http://przemol.blogspot.com/
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> -------------------------------------------------
> Dzwon TANIO w swieta!
> Sprawdz >> http://linkint.pl/f298c
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> http://www.freelists.org/webpage/oracle-l
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Received on Wed Apr 20 2011 - 18:05:22 CDT