Messages in this thread | | | Date | Thu, 27 Nov 2008 13:25:59 +0100 | From | "stephane eranian" <> | Subject | Re: [patch 20/24] perfmon: system calls interface |
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Hi,
Given that this thread discusses the syscall API, I would like to verify something with you at this point.
The sys_pfm_create() syscall is used to create a perfmon session (context). In the current patchset, where only counting is supported, the syscall is defined as:
int pfm_create(int flags, pfarg_sinfo_t *sif);
The plan is to extend this syscall, instead of adding a new syscall, to add support for sampling. The syscall would be used to select which sampling buffer format and for passing potential arguments to that format. The syscall would then look like:
int pfm_create(int flags, pfarg_sinfo_t *sif, char *fmt_name, void *fmt_arg, size_t arg_sz);
The kernel would look at the last 3 arguments ONLY if it saw the PFM_FL_SMPL_FMT bit set in flags. We follow the model used by open(2).
I want to double-check that you are fine with this approach.
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