linux/tools/perf/util/tsc.c
Leo Yan d110162caf perf tsc: Support cap_user_time_short for event TIME_CONV
The synthesized event TIME_CONV doesn't contain the complete parameters
for counters, this will lead to wrong conversion between counter cycles
and timestamp.

This patch extends event TIME_CONV to record flags 'cap_user_time_zero'
which is used to indicate the counter parameters are valid or not, if
not will directly return 0 for timestamp calculation.  And record the
flag 'cap_user_time_short' and its relevant fields 'time_cycles' and
'time_mask' for cycle calibration.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kemeng Shi <shikemeng@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Gasson <nick.gasson@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Remi Bernon <rbernon@codeweavers.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steve Maclean <steve.maclean@microsoft.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zou Wei <zou_wei@huawei.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20200914115311.2201-5-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-09-22 13:46:40 -03:00

113 lines
2.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <linux/compiler.h>
#include <linux/perf_event.h>
#include <linux/stddef.h>
#include <linux/types.h>
#include <asm/barrier.h>
#include "event.h"
#include "synthetic-events.h"
#include "debug.h"
#include "tsc.h"
u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
{
u64 t, quot, rem;
t = ns - tc->time_zero;
quot = t / tc->time_mult;
rem = t % tc->time_mult;
return (quot << tc->time_shift) +
(rem << tc->time_shift) / tc->time_mult;
}
u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
{
u64 quot, rem;
if (tc->cap_user_time_short)
cyc = tc->time_cycles +
((cyc - tc->time_cycles) & tc->time_mask);
quot = cyc >> tc->time_shift;
rem = cyc & (((u64)1 << tc->time_shift) - 1);
return tc->time_zero + quot * tc->time_mult +
((rem * tc->time_mult) >> tc->time_shift);
}
int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
struct perf_tsc_conversion *tc)
{
u32 seq;
int i = 0;
while (1) {
seq = pc->lock;
rmb();
tc->time_mult = pc->time_mult;
tc->time_shift = pc->time_shift;
tc->time_zero = pc->time_zero;
tc->time_cycles = pc->time_cycles;
tc->time_mask = pc->time_mask;
tc->cap_user_time_zero = pc->cap_user_time_zero;
tc->cap_user_time_short = pc->cap_user_time_short;
rmb();
if (pc->lock == seq && !(seq & 1))
break;
if (++i > 10000) {
pr_debug("failed to get perf_event_mmap_page lock\n");
return -EINVAL;
}
}
if (!tc->cap_user_time_zero)
return -EOPNOTSUPP;
return 0;
}
int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
struct perf_tool *tool,
perf_event__handler_t process,
struct machine *machine)
{
union perf_event event = {
.time_conv = {
.header = {
.type = PERF_RECORD_TIME_CONV,
.size = sizeof(struct perf_record_time_conv),
},
},
};
struct perf_tsc_conversion tc;
int err;
if (!pc)
return 0;
err = perf_read_tsc_conversion(pc, &tc);
if (err == -EOPNOTSUPP)
return 0;
if (err)
return err;
pr_debug2("Synthesizing TSC conversion information\n");
event.time_conv.time_mult = tc.time_mult;
event.time_conv.time_shift = tc.time_shift;
event.time_conv.time_zero = tc.time_zero;
event.time_conv.time_cycles = tc.time_cycles;
event.time_conv.time_mask = tc.time_mask;
event.time_conv.cap_user_time_zero = tc.cap_user_time_zero;
event.time_conv.cap_user_time_short = tc.cap_user_time_short;
return process(tool, &event, NULL, machine);
}
u64 __weak rdtsc(void)
{
return 0;
}