Why is MySQL nearly twice as fast on Linux?

[JG]

At 08:46 PM 5/23/2004 +0300, you wrote:
>JG wrote:
>
>>
>>You mean where I have the 3 instances of mysqld running in top?  You have 
>>~30 instances?
>I´m running the supersmack with $1=30.

(For those reading this thread who have not looked at the super-smack 
source code,
which I'm sure most have not, what Pete means by $1 is the number of 
simultaneous
supersmack client connections to run, even though it would be $2 from shell
ie:   super-smack smackfile-to-run clients rounds-per-client)


Anyway Pete, I am running the supersmack with 30 clients as well.

But that isn't what I asked you.

I have 30 supersmack clients running in top -H when the test is running (if 
I ran it with 30 clients anyway).

What I don't have is 30 mysqld instances (I had 3, as shown), and that is 
what you made it sound like you had.

You said:

"You seem to have a very small number of active threads. When I tried 
supersmack on fairly old machine (800MHz dual pentium) I get ~30 active 
mysql threads using CPU between 1.5% and 3.5%."

So if this is not the case, please clarify.

Or better...  post your top -H while tests are running as well as the 
super-smack command you ran.


>>I know that this FreeBSD/AMD64 reports that it is using ACPI... how do I 
>>find out if its using timecounters, or using them properly?
>kern.timecounter.hardware: ACPI-fast
>
>But I'm suspecting that the system call overhead between Linux and freebsd 
>differs enough to cause the results. If anything can be done about it, I 
>don´t know.

$ sysctl -a | grep 'ACPI'
kern.timecounter.hardware: ACPI-fast
kern.timecounter.choice: TSC(800) ACPI-fast(1000) i8254(0) dummy(-1000000)


Looks like I'm ok there (on FreeBSD/AMD64).


- Jeremy