Erik, On Tue, Jul 15, 2008 at 4:38 PM, Erik Junberger <[EMAIL PROTECTED]> wrote: > >>> If I for instance set the /reg_value, reg_long_reset, reg_short_reset/ >>> and /pfm_pebs_core_smpl_arg_t.cnt_reset/ to -10000 (on pmd0), the values >>> are initially set correctly. Every time pmd0 wraps around however, the >>> lower 32-bits of pmd0 will be set to 0, and the upper 32 to 1. This >>> effectively means that I can't choose any other sampling period than 2³². >>> When I read the /pfm_ds_area_core_t.pebs_cnt_reset/ value, the correct >>> reset value is always returned, but this doesn't reflect reality. >>> >>> >> >> With PEBS, you sampling value can only be 32-bit wide due to the wrmsrl() >> restriction that it can only modify the lower 32 bits. In fact you >> actually have >> 31-bits, bit 31 being the sign bit. >> > > I see. This should be sufficient though. > Yes, for any type of sampling.
> Yes, the concept of amortizing the cost of many samples is clear to me. But > I never get any interrupts at all. > I have also tried to have a separate thread do /read(fd, &msg, sizeof(msg))/ > during the execution of the program. This call never returns. > Also the /pebs_index /value never changes during execution, indicating that > no samples are written to memory, if I am not mistaken? > You need to set the PFM_REGL_OVFL_NOTIFY on the PMD. > Shouldn't it also be impossible for pmd0 to reach a value lower than 2^64 - > cnt_reset? Or is bit 31 to be considered a sign bit even in perfmon's > virtual 64-bit counters? Internally perfmon will set the upper bits according to the width of the counter. From your point-of-view, consider the counter as 64-bit. There is only one restriction w.r.t. to cnt_reset, make sure your sampling period fits 31-bits. > This seems to work fine, as I am at least getting some samples > Then you must be missing a flag somewhere. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ perfmon2-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
