Ticket #36921

Affinity bug

Open Date: 2017-01-06 03:31 Last Update: 2019-07-31 07:16

Reporter:
(Anonymous)
Owner:
Type:
Status:
Open [Owner assigned]
Component:
(None)
MileStone:
(None)
Priority:
6
Severity:
6
Resolution:
None
File:
None

Details

Please, add the -n parameter to the diskspd command line when 1 thread benchmark is started; this is the way one thread applications run; otherwise the benchmark will be set to run on the CPU 0 (default affinity)

-n disable default affinity (-a)

ashafranov@hotmail.com

Ticket History (3/3 Histories)

2017-01-06 03:31 Updated by: None
  • New Ticket "Affinity bug" created
2017-05-25 15:55 Updated by: None
Comment

This may be what the original poster found.

This happens only in Windows 10, single thread test and the size of read/write is small. e.g. a lot of random synchronous read. In this case, set the affinity in fact increases the read/write performance. A closer look at it, the average time of Readfile()/Writefile() is shorter with the affinity set.

cj.tsai(at)yandex.com

2019-07-31 07:16 Updated by: None
Comment

https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-setthreadaffinitymask

Setting an affinity mask for a process or thread can result in threads receiving less processor time, as the system is restricted from running the threads on certain processors. In most cases, it is better to let the system select an available processor. If the new thread affinity mask does not specify the processor that is currently running the thread, the thread is rescheduled on one of the allowable processors.

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