On 10/06/2014 06:47 μμ, Dirk Brandewie wrote: > On 06/09/2014 02:00 PM, Stratos Karafotis wrote: >> Add stats file in debugfs under driver's parent directory >> (pstate_snb) which counts the time in nsecs per requested >> P state and the number of times the specific state >> was requested. >> >> The file presents the statistics per logical CPU in the >> following format. The time is displayed in msecs: >> > > NAK > > This adds significantly to the memory footprint to gather information > that is available by post processing the perf tracepoint information. > The increase isn't horrible on single socket desktop processor machines > but gets big with server class machines. One vendor I have talked to > considers > a machine with 1024 cpus to be a SMALL machine. >
If I am not wrong the sizeof pstate_stat is 20B. On my CPU with 20 P states, we need 400B per logical CPU (3200B total in my desktop) plus 64B for stats pointers. In your example this would need about 400KB - 500KB? Is it too much for 1024 a CPUs system? I think it's a useful piece of info that we can have it directly without post processing tracepoint. Is it acceptable to conditionally compile it with a new CONFIG option? Thanks, Stratos -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
