# About ios FMOD::Thread::callback wakeups count

**URL:** <https://qa.fmod.com/t/about-ios-fmod-callback-wakeups-count/20826>\
**Category:** FMOD Engine\
**Tags:** ios, ue4, cpp\
**Created:** [November 1, 2023, 3:56am UTC](https://qa.fmod.com/t/about-ios-fmod-callback-wakeups-count/20826 "2023-11-01T03:56:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![yinchao](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/yinchao/32/521_2.png) [@yinchao](https://qa.fmod.com/u/yinchao)\
**Post date:** [November 1, 2023, 3:56am UTC](https://qa.fmod.com/t/about-ios-fmod-callback-wakeups-count/20826/1 "2023-11-01T03:56:13Z")

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Hi，We recently discovered that on the IOS side, there are too many background wakeups and the client is killed. Using the Xcode tool, we found that the FMOD callback thread in the background has frequent user mode and kernel mode problems with a frequency of about 10 milliseconds. Is there any interface that can control the FMOD callback thread in the background Wake-up frequency interface. Thanks。

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<div class="post-metadata">

**Author:** ![jeff\_fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/jeff_fmod/32/1766_2.png) [@jeff\_fmod](https://qa.fmod.com/u/jeff_fmod)\
**Post date:** [November 6, 2023, 6:04am UTC](https://qa.fmod.com/t/about-ios-fmod-callback-wakeups-count/20826/2 "2023-11-06T06:04:25Z")

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You can indirectly control the frequency of the mixer by changing the [dsp buffer size](https://fmod.com/docs/2.02/api/core-api-system.html#system_setdspbuffersize) and/or [sample rate](https://fmod.com/docs/2.02/api/core-api-system.html#system_setsoftwareformat).  
For iOS, changing the `blocksize` to 2048 should give you an update frequency of 20ms.  
Can you please give that a shot and let me know if you are still getting crashes?