[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

[linux-lvm] Re: [HACKERS] PostgreSQL block size vs. LVM2 stripe width



Mark,

how often did you run your tests?  Are the results reproduceable?

On Fri, 26 Mar 2004 14:00:01 -0800 (PST), markw osdl org wrote:
>                        Linux-2.6.3, LVM2 Stripe Width
>                        (going across)
>PostgreSQL
>BLCKSZ
>(going down)    16 KB   32 KB   64 KB   128 KB  256 KB  512 KB
>2 KB            2617    2656    2652    2664    2667    2642
>4 KB            4393    4486    4577    4557    4511    4448
>8 KB            4337    4423    4471    4576    4111    3642
>16 KB           4412    4495    4532    4536    2985    2312
>32 KB           3705    3784    3886    3925    2936    2362

Unless someone can present at least an idea of a theory why a BLCKSZ of
8 KB is at a local minimum (1 or 2% below the neighbouring values) for
stripe widths up to 64 KB I'm not sure whether we can trust these
numbers.

Before I hit the send button, I did a quick check of the link you
provided.  The links in the table contain the following test numbers:

        16 KB   32 KB   64 KB   128 KB  256 KB  512 KB
2 KB     72      71      70       69      66      65
4 KB     64      63      62       61      60      58
8 KB     54      53      52       51      50      49
16 KB    79      78      77       76      75      74
32 KB    86      85      84       83      82      80

Does this mean that you first ran all test with 8 KB, then with 4, 2, 16
and 32 KB BLCKSZ?  If so, I suspect that you are measuring the effects
of something different.

Servus
 Manfred

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]