Messages in this thread | | | Date | Wed, 25 Mar 2009 14:35:00 -0700 | From | Corey Ashford <> | Subject | Re: [tip:perfcounters/core] perf_counter: record time running and time enabled for each counter |
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Paul Mackerras wrote: > Commit-ID: 03ced439c94d692363307eeb3abe0bbfa2d08a01 > Gitweb: http://git.kernel.org/tip/03ced439c94d692363307eeb3abe0bbfa2d08a01 > Author: Paul Mackerras <paulus@samba.org> > AuthorDate: Wed, 25 Mar 2009 22:46:58 +1100 > Committer: Ingo Molnar <mingo@elte.hu> > CommitDate: Wed, 25 Mar 2009 13:24:00 +0100 > > perf_counter: record time running and time enabled for each counter [snip] > These values can be supplied to userspace on a read from the counter. > Userspace requests that they be supplied after the counter value by > setting the PERF_FORMAT_TOTAL_TIME_ENABLED and/or > PERF_FORMAT_TOTAL_TIME_RUNNING bits in the hw_event.read_format field > when creating the counter. (There is no way to change the read format > after the counter is created, though it would be possible to add some > way to do that.)
This change looks good to me, except:
How do I know which value comes first after the counter value if I have both PERF_FORMAT_TOTAL_TIME_ENABLED and PERF_FORMAT_TOTAL_TIME_RUNNING set? Are they in the order of their enum values? The order should be described somewhere. Is there anything to keep a kernel code change from inadvertantly reversing the position of two values at some point in the future?
Regards,
- Corey
Corey Ashford Software Engineer IBM Linux Technology Center, Linux Toolchain Beaverton, OR 503-578-3507 cjashfor@us.ibm.com
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