Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hello, after reading the available documentation in DRBD User-Guide (http://www.drbd.org/users-guide/s-latency-tuning.html#s-latency-tuning-cpu-mask) ... A mask of 12 (00001100) implies DRBD may use the third and fourth CPU. ... and the man page drbd.conf: ... The default value of cpu-mask is 0, which means that DRBD's kernel threads should be spread over all CPUs of the machine. This value must be given in hexadecimal notation. ... I set the config parameter cpu-mask in drbd.conf to 255 (to enable usage of all 8 available cores) but got this: # ps u 4387 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 4387 3.5 0.0 0 0 ? S 2010 1539:29 [drbd0_worker] # taskset -c -p 4387 pid 4387's current affinity list: 0,2,4,6 But expected this list: 0,1,2,3,4,5,6,7 => Conclusion: 1. The example in DRBD User-Guide is simply wrong (drbd.conf: "cpu-mask 12;" => affinity list: 1,4) 2. The cpu-mask parameter has to be specified, as stated in the man page, as Hexstring ("cpu-mask ff;" to get the first 8 cpus) in drbd.conf 3. But if the parameter cpu-mask is explicit set to zero in drbd.conf (to get it run on _all_ cpus) I get only the second cput (affinity list: 1). So in this aspect the man page is wrong about the default. @linbit: Could this be fixed in User-Guide and man page And I'm not sure, if it can safely fixed by setting the mask on running [drbd1_worker], [drbd1_receiver] and [drbd1_asender] tasks like this: taskset -c -p 0-7 <drbdX_yyy pids> (Because I won't like to shutdown drbd resources on primary) Or may this triggers some race condition and drbd hangs or show other erratic behaviour? Kind Regards, Roland -- Roland.Friedwagner at wu.ac.at Phone: +43 1 31336 5377 IT Services - WU (Vienna University of Economics and Business)