Make BUF_READ_AHEAD_AREA a constant

Do you understand the patch?
This patch simply doesn't startup when small BP.
Useless patch for us....

Yasufumi,

So we need to make it working with default BP also.

On Fri, Jul 23, 2010 at 5:20 AM, Yasufumi Kinoshita
<email address hidden> wrote:
> Do you understand the patch?
> This patch simply doesn't startup when small BP.
> Useless patch for us....
>
> --
> Make BUF_READ_AHEAD_AREA a constant
> https://bugs.launchpad.net/bugs/606811
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Vadim,

The patch is not
"Make BUF_READ_AHEAD_AREA a constant".

But "Don't start up when small BP for which 64 page BUF_READ_AHEAD_AREA is too large".

So. I don't understand "working with default BP" meaning.
The patch is for "don't start up when small BP such as default".

And for small BP, BUF_READ_AHEAD_AREA should not be 64. it is too large.
(e.g. BP = 8MB, read ahed 1MB? why do you think it is needed?)

Yasufumi,

The patch is to avoid expensive call
ut_min(64, ut_2_power_up(buf_pool->curr_size / 32))

function ut_2_power_up is CPU time consuming and not needed if we work
with big BP

On Fri, Jul 23, 2010 at 10:17 AM, Yasufumi Kinoshita
<email address hidden> wrote:
> Vadim,
>
> The patch is not
> "Make BUF_READ_AHEAD_AREA a constant".
>
> But "Don't start up when small BP for which 64 page BUF_READ_AHEAD_AREA is too large".
>
> So. I don't understand "working with default BP" meaning.
> The patch is for "don't start up when small BP such as default".
>
> And for small BP, BUF_READ_AHEAD_AREA should not be 64. it is too large.
> (e.g. BP = 8MB, read ahed 1MB? why do you think it is needed?)
>

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Phone +1-888-401-3403,  Skype: vadimtk153
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OK..
Do you mean to change the default and min size of BP to 32MB?
If so, I understand.

I will merge the patch to innodb_io_patches.patch later.

32MB default for BP
and
#define BUF_READ_AHEAD_AREA 64
is OK for me

On Fri, Jul 23, 2010 at 10:34 AM, Yasufumi Kinoshita
<email address hidden> wrote:
> OK..
> Do you mean to change the default and min size of BP to 32MB?
> If so, I understand.
>
> I will merge the patch to innodb_io_patches.patch later.
>
> --
> Make BUF_READ_AHEAD_AREA a constant
> https://bugs.launchpad.net/bugs/606811
> You received this bug notification because you are a member of Percona
> developers, which is the registrant for Percona Server.
>
> Status in Percona Server with XtraDB: In Progress
>
> Bug description:
> see http://bazaar.launchpad.net/~mysqlatfacebook/mysqlatfacebook/5.1/revision/3538
>
>
>

--
Vadim Tkachenko, CTO, Percona Inc.
Phone +1-888-401-3403,  Skype: vadimtk153
Schedule meeting: http://tungle.me/VadimTkachenko

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I still don't believe the effect of the patch.
little improvement of CPU resource at IO operation may not show effect.

Yasufumi, Vadim,

What performance gains are we getting when it is constant ?
Can it be variable which is computed once on start rather than
constant (it looks like this would be similar speed for me)

If we need to set it to constant what is the minimum buffer pool
with which it is going to work ?

I think we can safely increase minimum buffer pool to 64M or so
in Percona Server (and change default) - If we ever will need to support
customers with very small systems we can consider having special build for
these.

On Fri, Jul 23, 2010 at 12:17 AM, Yasufumi Kinoshita <
<email address hidden>> wrote:

> Vadim,
>
> The patch is not
> "Make BUF_READ_AHEAD_AREA a constant".
>
> But "Don't start up when small BP for which 64 page BUF_READ_AHEAD_AREA
> is too large".
>
> So. I don't understand "working with default BP" meaning.
> The patch is for "don't start up when small BP such as default".
>
> And for small BP, BUF_READ_AHEAD_AREA should not be 64. it is too large.
> (e.g. BP = 8MB, read ahed 1MB? why do you think it is needed?)
>
> --
> Make BUF_READ_AHEAD_AREA a constant
> https://bugs.launchpad.net/bugs/606811
> You received this bug notification because you are a member of Percona
> developers, which is the registrant for Percona Server.
>
> Status in Percona Server with XtraDB: In Progress
>
> Bug description:
> see
> http://bazaar.launchpad.net/~mysqlatfacebook/mysqlatfacebook/5.1/revision/3538
>
>
>

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innodb_io_patches.patch of release-5.1.49-12 were already fixed.

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-1148