Waiting for shared memory?


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Questions and Answers : Preferences : Waiting for shared memory?

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SDevenshire
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Message 1510947 - Posted: 1 May 2014, 21:10:12 UTC

Hi Folks,

I'm on a system with more than 8 threads but Seti is only using 8 and I get the "Waiting for shared memory." message for other tasks. What is the secret to get Seti to use all the threads on my system?

Thanks
SD
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John McLeod VII
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Message 1511226 - Posted: 2 May 2014, 11:48:45 UTC - in response to Message 1510947.

By threads, do you mean processors?
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BOINC WIKI

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Message 1511364 - Posted: 2 May 2014, 16:29:33 UTC

From http://boincfaq.mundayweb.com/index.php?view=276:

BOINC science applications use shared memory to communicate with the core client, and a certain amount is reserved for each current task, whether running or waiting. The default configuration of a multi-CPU Mac (regardless of how much RAM is installed) is sometimes inadequate to support several projects at once.

If you get this error message, which is usually followed by a “Couldn't start or resume: -144” error in the current computation, it may help to set your BOINC general preference “Leave applications in memory while suspended?” to no; however, the problem will probably just become less frequent rather than being solved, and moreover some projects’ applications, those that save checkpoints infrequently (or erratically), may not take well to this setting.

A better solution is available—if you don’t mind reconfiguring your system’s kernel a littleThe method, accompanied by a more detailed description of the issue, is outlined in Configuring Shared Memory on Mac OS X from Spy Hill Research (hosts of the BOINC Pirates@home project)(original link doesn't work anymore). It involves creating a text file “/etc/sysctl.conf” that contains the following commands:

kern.sysv.shmmax=16777216 kern.sysv.shmmin=1 kern.sysv.shmmni=128 kern.sysv.shmseg=32 kern.sysv.shmall=4096


and rebooting the computer. This will quadruple the default allocation of shared memory.

Note that the problem may manifest with slightly different error messages: “Can't create shared memory: system shmat” followed by “Couldn't start or resume: -146”.

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Message 1511551 - Posted: 2 May 2014, 23:23:21 UTC - in response to Message 1511364.

The method, accompanied by a more detailed description of the issue, is outlined in Configuring Shared Memory on Mac OS X from Spy Hill Research (hosts of the BOINC Pirates@home project)
(original link doesn't work anymore).

The link can still be seen on 'Wayback Machine':

Configuring Shared Memory on Mac OS X
http://web.archive.org/web/20130516144758/http://www.spy-hill.net/help/apple/SharedMemory.html
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Questions and Answers : Preferences : Waiting for shared memory?

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