# glDispatchCompute calling overhead

**URL:** <https://community.khronos.org/t/gldispatchcompute-calling-overhead/71774>\
**Category:** OpenGL: Advanced Coding\
**Created:** [April 23, 2014, 11:45am UTC](https://community.khronos.org/t/gldispatchcompute-calling-overhead/71774 "2014-04-23T11:45:45Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![edoreshef](https://community.khronos.org/letter_avatar_proxy/v4/letter/e/aeb1de/32.png) [@edoreshef](https://community.khronos.org/u/edoreshef)\
**Post date:** [April 23, 2014, 11:45am UTC](https://community.khronos.org/t/gldispatchcompute-calling-overhead/71774/1 "2014-04-23T11:45:45Z")

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Dear Gurus,

I’m facing an annoying problem (or is really?) that every call to glDispatchCompute ALLWAYS comes with an annoying overhead of about 0.2ms.  
Just make it clear: Even executing a “glDispatchCompute(0,0,0)” call on an EMPTY shader cost 0.2ms.

Questions: [ol]  
[li]Does this make sense?[/li][li]Is it NVIDIA only issue?[/li][li]Is there a way around this?[/li][/ol]

\*Note1: The 0.2ms is measured using “glBeginQuery(GL\_TIME\_ELAPSED,…)“  
\*Note2: Platform is GTX-560, Windows 7, Latest NVIDIA drivers.

Thanks guys!

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<div class="post-metadata">

**Author:** ![inutard](https://community.khronos.org/user_avatar/community.khronos.org/inutard/32/2631_2.png) [@inutard](https://community.khronos.org/u/inutard)\
**Post date:** [May 12, 2014, 3:55am UTC](https://community.khronos.org/t/gldispatchcompute-calling-overhead/71774/2 "2014-05-12T03:55:25Z")

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I am also having this issue. I get the exact same delay ~0.2ms when measuring with glBeginQuery(GL\_TIME\_ELAPSED, …).

For reference, I am on Windows 7 with GTX-470 on the latest drivers.

Could someone shed some light on this?

EDIT: I have just tried the same thing on a GTX-780 and the delay disappeared. I guess the delay was something only present in 560 and below?