Variable PHP-mySQL response time on Suse 8.2 dual-processor

[Alan Hewat]

I have a relatively modest mySQL database with a PHP interface (70,000
entries). On a standard Dell Dimension 4400 (1.9 GHz with 512 Mbytes)
running Suse 8.1 a typical query takes 0.66 sec with no other system
load (http://icsd.ill.fr/)

On a new IBM dual processor XEON 2.4GHZ (1 GO RAM & 2 SCSI disks)
running Suse 8.2 the same query (with no other system load) takes
anywhere between 0.5 and 3.0 seconds - randomly variable response for
no obvious reason ! With only one query, only one processor is being
used, but why is the response so variable ? What can I try to track
down the problem ? After searching Google, I tried playing with renice
and my.cnf variables (below) but that made no difference.

skip-locking
set-variable = key_buffer=384M
set-variable = max_allowed_pac ket=1M
set-variable = table_cache=512
set-variable = sort_buffer=2M
set-variable = record_buffer=2 M
set-variable = thread_cache=8
# Try number of CPU's*2 for thread_concurre ncy
set-variable = thread_concurre ncy=4
set-variable = myisam_sort_buf fer_size=64M

I am not a database/system expert - just a scientist trying to use
these things.

Alan <He***@ill.fr >

[D. Pickering]

1. Do desc table name and make sure keys are the same and that there are
keys defined and used in the query
2. maybe try "explain yourentirequery " to see if it's using the defined keys
as expected
3. open a second shell and run w or top while doing the query....what for
other processes eating up the machine.
4. if needed, put the query into a loop to keep it running.
that's sure a disappointment isn't it. big machine and slower, and almost
worse: inconsistent.
dp

"Alan Hewat" <he***@ill.fr > wrote in message
news:9f******** *************** ***@posting.goo gle.com...

I have a relatively modest mySQL database with a PHP interface (70,000
entries). On a standard Dell Dimension 4400 (1.9 GHz with 512 Mbytes)
running Suse 8.1 a typical query takes 0.66 sec with no other system
load (http://icsd.ill.fr/)

On a new IBM dual processor XEON 2.4GHZ (1 GO RAM & 2 SCSI disks)
running Suse 8.2 the same query (with no other system load) takes
anywhere between 0.5 and 3.0 seconds - randomly variable response for
no obvious reason ! With only one query, only one processor is being
used, but why is the response so variable ? What can I try to track
down the problem ? After searching Google, I tried playing with renice
and my.cnf variables (below) but that made no difference.

skip-locking
set-variable = key_buffer=384M
set-variable = max_allowed_pac ket=1M
set-variable = table_cache=512
set-variable = sort_buffer=2M
set-variable = record_buffer=2 M
set-variable = thread_cache=8
# Try number of CPU's*2 for thread_concurre ncy
set-variable = thread_concurre ncy=4
set-variable = myisam_sort_buf fer_size=64M

I am not a database/system expert - just a scientist trying to use
these things.

Alan <He***@ill.fr >

[D. Pickering]

1. Do desc table name and make sure keys are the same and that there are
keys defined and used in the query
2. maybe try "explain yourentirequery " to see if it's using the defined keys
as expected
3. open a second shell and run w or top while doing the query....what for
other processes eating up the machine.
4. if needed, put the query into a loop to keep it running.
that's sure a disappointment isn't it. big machine and slower, and almost
worse: inconsistent.
dp

"Alan Hewat" <he***@ill.fr > wrote in message
news:9f******** *************** ***@posting.goo gle.com...

I have a relatively modest mySQL database with a PHP interface (70,000
entries). On a standard Dell Dimension 4400 (1.9 GHz with 512 Mbytes)
running Suse 8.1 a typical query takes 0.66 sec with no other system
load (http://icsd.ill.fr/)

On a new IBM dual processor XEON 2.4GHZ (1 GO RAM & 2 SCSI disks)
running Suse 8.2 the same query (with no other system load) takes
anywhere between 0.5 and 3.0 seconds - randomly variable response for
no obvious reason ! With only one query, only one processor is being
used, but why is the response so variable ? What can I try to track
down the problem ? After searching Google, I tried playing with renice
and my.cnf variables (below) but that made no difference.

skip-locking
set-variable = key_buffer=384M
set-variable = max_allowed_pac ket=1M
set-variable = table_cache=512
set-variable = sort_buffer=2M
set-variable = record_buffer=2 M
set-variable = thread_cache=8
# Try number of CPU's*2 for thread_concurre ncy
set-variable = thread_concurre ncy=4
set-variable = myisam_sort_buf fer_size=64M

I am not a database/system expert - just a scientist trying to use
these things.

Alan <He***@ill.fr >