Hi,
Maximum size of the primary thread pool - the default is 16. Is it recommended to increase this value to higher ones like 32/64 etc. Is there any loose relation between the RAM and OS and the thread pool size that I need to consider.
Simply, is there any guideline on this thread pool size and it's implications?
Rajarshi Chaudhuri Genesys Telecommunications Lab, Inc rajarshi@genesyslab.com mailto:rajarshi@genesyslab.com
--On Thursday, February 08, 2007 11:34 AM -0800 Rajarshi Chaudhuri rajarshi@genesyslab.com wrote:
Hi,
Maximum size of the primary thread pool - the default is 16. Is it recommended to increase this value to higher ones like 32/64 etc. Is there any loose relation between the RAM and OS and the thread pool size that I need to consider.
Simply, is there any guideline on this thread pool size and it's implications?
All testing I've done of OpenLDAP has generally indicated the best performance occurs at a maximum of 8 threads. How slapd behaves in your environment may be different, and the best way to know is to test how the server behaves for you with different thread settings. Some servers (like the Sun Niagra systems) do reasonable well with 16 or 32 threads.
--Quanah
-- Quanah Gibson-Mount Principal Software Developer ITS/Shared Application Services Stanford University GnuPG Public Key: http://www.stanford.edu/~quanah/pgp.html
Rajarshi Chaudhuri wrote:
Hi,
Maximum size of the primary thread pool - the default is 16. Is it recommended to increase this value to higher ones like 32/64 etc.
We would never recommend any particular value for any particular purpose. Without knowing the specifics of a system environment and usage patterns, such recommendations would be meaningless.
Is there any loose relation between the RAM and OS and the thread pool size that I need to consider.
Yes, each thread uses 4 or 8MB of memory for its runtime stack. (8MB on 64 bit machines). Plus there are a variety of other modules that allocate things on a per-thread basis.
Simply, is there any guideline on this thread pool size and it’s implications?
The guideline is "test your server at varying configurations and choose what works best for you." The effectiveness of threading varies with machine architecture, OS revision, and C library revision. Increasing the thread count eventually reaches a point of zero-gain as the thread scheduling overhead starts to overshadow the time spent actually executing user code. This is a fundamental feature of threading, on any system with any software.
Rajarshi Chaudhuri Genesys Telecommunications Lab, Inc rajarshi@genesyslab.com mailto:rajarshi@genesyslab.com
Thanks Howard - I'll vary the pool size and watch the impact under load.
One more question regarding threads - is there a relation between the concurrency directive and the threads directive in slapd.conf?
Rajarshi Chaudhuri Genesys Telecommunications Lab, Inc rajarshi@genesyslab.com 650.466.4860
-----Original Message----- From: Howard Chu [mailto:hyc@symas.com] Sent: Thursday, February 08, 2007 3:45 PM To: Rajarshi Chaudhuri Cc: openldap-software@openldap.org Subject: Re: Maximum size of the primary thread pool
Rajarshi Chaudhuri wrote:
Hi,
Maximum size of the primary thread pool - the default is 16. Is it recommended to increase this value to higher ones like 32/64 etc.
We would never recommend any particular value for any particular purpose. Without knowing the specifics of a system environment and usage patterns, such recommendations would be meaningless.
Is there any loose relation between the RAM and OS and the thread pool
size
that I need to consider.
Yes, each thread uses 4 or 8MB of memory for its runtime stack. (8MB on 64 bit machines). Plus there are a variety of other modules that allocate things on a per-thread basis.
Simply, is there any guideline on this thread pool size and it's implications?
The guideline is "test your server at varying configurations and choose what works best for you." The effectiveness of threading varies with machine architecture, OS revision, and C library revision. Increasing the thread
count eventually reaches a point of zero-gain as the thread scheduling overhead starts to overshadow the time spent actually executing user code. This is a fundamental feature of threading, on any system with any software.
Rajarshi Chaudhuri Genesys Telecommunications Lab, Inc rajarshi@genesyslab.com mailto:rajarshi@genesyslab.com
Rajarshi Chaudhuri wrote:
Thanks Howard - I'll vary the pool size and watch the impact under load.
One more question regarding threads - is there a relation between the concurrency directive and the threads directive in slapd.conf?
Maybe, maybe not. On most systems the concurrency directive is a no-op. On a POSIX-thread based system, this value is passed to pthread_setconcurrency. This setting only means something if the underlying thread model is M:N, i.e., the number of user threads differs from the number of kernel threads. This was true on some versions of Solaris, as I recall. I don't know any other examples offhand.
Rajarshi Chaudhuri Genesys Telecommunications Lab, Inc rajarshi@genesyslab.com 650.466.4860
-----Original Message----- From: Howard Chu [mailto:hyc@symas.com] Sent: Thursday, February 08, 2007 3:45 PM To: Rajarshi Chaudhuri Cc: openldap-software@openldap.org Subject: Re: Maximum size of the primary thread pool
Rajarshi Chaudhuri wrote:
Hi,
Maximum size of the primary thread pool - the default is 16. Is it recommended to increase this value to higher ones like 32/64 etc.
We would never recommend any particular value for any particular purpose. Without knowing the specifics of a system environment and usage patterns, such recommendations would be meaningless.
Is there any loose relation between the RAM and OS and the thread pool
size
that I need to consider.
Yes, each thread uses 4 or 8MB of memory for its runtime stack. (8MB on 64 bit machines). Plus there are a variety of other modules that allocate things on a per-thread basis.
Simply, is there any guideline on this thread pool size and it's implications?
The guideline is "test your server at varying configurations and choose what works best for you." The effectiveness of threading varies with machine architecture, OS revision, and C library revision. Increasing the thread
count eventually reaches a point of zero-gain as the thread scheduling overhead starts to overshadow the time spent actually executing user code. This is a fundamental feature of threading, on any system with any software.
Rajarshi Chaudhuri Genesys Telecommunications Lab, Inc rajarshi@genesyslab.com mailto:rajarshi@genesyslab.com
openldap-software@openldap.org
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Howard Chu -
Quanah Gibson-Mount -
Rajarshi Chaudhuri