How to setup Litespeed LSWS for a shared environment?

[mistwang]

If you got some spare memory in your server not being actively used, there is one tip to improve PHP and overall server performance.

Requirements:

* there are enough free memory to spare.
* /dev/shm/ should be mounted as tmpfs.

Install eaccelerator with PHP suEXEC, set disk cache storage to /dev/shm/eaccelerator/ instead of /tmp/eaccelerator/, then add a cron job to clean the cache directory every 5-10 minutes, so cache files not being used frequently will not fill up the precious shared memory storage.

Noticed that the server load going down from 4.x to 1.x on one client's server.

[DraCoola]

Originally Posted by mistwang

Noticed that the server load going down from 4.x to 1.x on one client's server.

On my server?
Thank you mistwang for your helps and advices

Btw on my eAccelerator, it could only caching from 1 to 19 scripts, maximum.
Or it perhaps caused by shm value/size has set to just 16mb?

Because if I increase it to more than 16mb, some of random pages will suddenly blank, not completely load, or shows an alien codes on it.

[anewday]

Do you mean the value for "eaccelerator.shm_size" ?

[Tony]

Originally Posted by mistwang

If you got some spare memory in your server not being actively used, there is one tip to improve PHP and overall server performance.

Requirements:

* there are enough free memory to spare.
* /dev/shm/ should be mounted as tmpfs.

Install eaccelerator with PHP suEXEC, set disk cache storage to /dev/shm/eaccelerator/ instead of /tmp/eaccelerator/, then add a cron job to clean the cache directory every 5-10 minutes, so cache files not being used frequently will not fill up the precious shared memory storage.

Noticed that the server load going down from 4.x to 1.x on one client's server.

Interesting.

We played around with eaccelerator a bit on one machine but for the density of our machines it's not even worth doing. We actually had higher i/o wait due to the amount of cached files it ended up writing. I think in the end we had about 12GB of cached files eccelerator does have a memory only feature but I did not see any real improvements. I'm guessing it has to do with the timeout of the PHP processes and such.

This /dev/shm idea seems interesting though. I might play around with that when we start deploying nehalem based servers with 12+GB of ram.

[DraCoola]

Originally Posted by anewday

Do you mean the value for "eaccelerator.shm_size" ?

Yes that is.
I've been with php as DSO (on Cpanel-Apache), and set the eaccelerator.shm_size to 2048 and that were fine.
Except it were doesn't fine on DSO-nobody security.

[Tony]

Originally Posted by DraCoola

Yes that is.
I've been with php as DSO (on Cpanel-Apache), and set the eaccelerator.shm_size to 2048 and that were fine.
Except it were doesn't fine on DSO-nobody security.

If my memory serves me right with PHP processes running as their user this changes the meaning of this slightly. The shm size would be on a per process or user basis I cannot remember which. So when you say a max of 2048 when running LSAPI or even FastCGI on Apache it's not doing shared between all the pools that's just one user set.

This is also why it gets confusing the reporting of eaccelerator you'd need the script for each user account to see the accurate numbers.

I'm pretty sure on most of this as I did some testing to see what exactly happens as I had never ran caching extensions when PHP was running as various users.

[mistwang]

Originally Posted by Tony

We played around with eaccelerator a bit on one machine but for the density of our machines it's not even worth doing. We actually had higher i/o wait due to the amount of cached files it ended up writing. I think in the end we had about 12GB of cached files eccelerator does have a memory only feature but I did not see any real improvements. I'm guessing it has to do with the timeout of the PHP processes and such.

Yes, that's true that it will cause high I/O wait if you use /tmp/eaccelerator/ as the storage. However, using /dev/shm/ is more like using a memory disk, which is lightening fast without increasing I/O wait.

[mistwang]

Originally Posted by DraCoola

Btw on my eAccelerator, it could only caching from 1 to 19 scripts, maximum.
Or it perhaps caused by shm value/size has set to just 16mb?

Because if I increase it to more than 16mb, some of random pages will suddenly blank, not completely load, or shows an alien codes on it.

No need to increase it or let it cache more pages in memory, as the disk cache is actually in memory, also PHP process will start/stop more frequently in PHP suEXEC mode for shared hosting. As long as PHP process can grab a copy of parsed PHP opcode from memory disk, it is fine.

[anewday]

Are these setting right to optimize? I'm confused on what value eaccelerator.shm_size should be if i set the disk cache to /dev/shm with 1.5G of space.


php.ini

extension_dir = "/usr/local/lsws/lsphp4/lib/php/extensions/no-debug-non-zts-20020429"
extension="eaccelerator.so"
eaccelerator.shm_size="64"
eaccelerator.cache_dir="/dev/shm/lswsphp4eacc"
eaccelerator.enable="1"                
eaccelerator.optimizer="1"
eaccelerator.check_mtime="1"
eaccelerator.debug="0"
eaccelerator.shm_max="0"                  
eaccelerator.shm_ttl="0"
eaccelerator.shm_prune_period="0"
eaccelerator.shm_only="0"
eaccelerator.compress="1"
eaccelerator.compress_level="9"
eaccelerator.keys="shm"
eaccelerator.sessions="shm"
eaccelerator.content="shm"

/etc/fstab

none                    /dev/shm                tmpfs   noexec,nosuid   0 0

df -h

none                  1.5G     0  1.5G   0% /dev/shm

[mistwang]

looks good to me.