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perf intel-pt: Fix MTC timestamp calculation for large MTC periods

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The MTC packet provides a 8-bit slice of CTC which is related to TSC by
the TMA packet, however the TMA packet only provides the lower 16 bits
of CTC.  If mtc_shift > 8 then some of the MTC bits are not in the CTC
provided by the TMA packet. Fix-up the last_mtc calculated from the TMA
packet by copying the missing bits from the current MTC assuming the
least difference between the two, and that the current MTC comes after
last_mtc.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org # v4.3+
Link: http://lkml.kernel.org/r/1475062896-22274-2-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2016-09-28 14:41:36 +03:00 committed by Arnaldo Carvalho de Melo
parent 51ee6481fa
commit 3bccbe20f6
1 changed files with 36 additions and 0 deletions
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36
tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
View file

@ -90,6 +90,7 @@ struct intel_pt_decoder {
bool pge;
bool have_tma;
bool have_cyc;
bool fixup_last_mtc;
uint64_t pos;
uint64_t last_ip;
uint64_t ip;
@ -586,10 +587,31 @@ struct intel_pt_calc_cyc_to_tsc_info {
uint64_t tsc_timestamp;
uint64_t timestamp;
bool have_tma;
bool fixup_last_mtc;
bool from_mtc;
double cbr_cyc_to_tsc;
};
/*
* MTC provides a 8-bit slice of CTC but the TMA packet only provides the lower
* 16 bits of CTC. If mtc_shift > 8 then some of the MTC bits are not in the CTC
* provided by the TMA packet. Fix-up the last_mtc calculated from the TMA
* packet by copying the missing bits from the current MTC assuming the least
* difference between the two, and that the current MTC comes after last_mtc.
*/
static void intel_pt_fixup_last_mtc(uint32_t mtc, int mtc_shift,
uint32_t *last_mtc)
{
uint32_t first_missing_bit = 1U << (16 - mtc_shift);
uint32_t mask = ~(first_missing_bit - 1);
*last_mtc |= mtc & mask;
if (*last_mtc >= mtc) {
*last_mtc -= first_missing_bit;
*last_mtc &= 0xff;
}
}
static int intel_pt_calc_cyc_cb(struct intel_pt_pkt_info *pkt_info)
{
struct intel_pt_decoder *decoder = pkt_info->decoder;
@ -619,6 +641,11 @@ static int intel_pt_calc_cyc_cb(struct intel_pt_pkt_info *pkt_info)
return 0;
mtc = pkt_info->packet.payload;
if (decoder->mtc_shift > 8 && data->fixup_last_mtc) {
data->fixup_last_mtc = false;
intel_pt_fixup_last_mtc(mtc, decoder->mtc_shift,
&data->last_mtc);
}
if (mtc > data->last_mtc)
mtc_delta = mtc - data->last_mtc;
else
@ -687,6 +714,7 @@ static int intel_pt_calc_cyc_cb(struct intel_pt_pkt_info *pkt_info)
data->ctc_delta = 0;
data->have_tma = true;
data->fixup_last_mtc = true;
return 0;
@ -753,6 +781,7 @@ static void intel_pt_calc_cyc_to_tsc(struct intel_pt_decoder *decoder,
.tsc_timestamp = decoder->tsc_timestamp,
.timestamp = decoder->timestamp,
.have_tma = decoder->have_tma,
.fixup_last_mtc = decoder->fixup_last_mtc,
.from_mtc = from_mtc,
.cbr_cyc_to_tsc = 0,
};
@ -1271,6 +1300,7 @@ static void intel_pt_calc_tma(struct intel_pt_decoder *decoder)
}
decoder->ctc_delta = 0;
decoder->have_tma = true;
decoder->fixup_last_mtc = true;
intel_pt_log("CTC timestamp " x64_fmt " last MTC %#x CTC rem %#x\n",
decoder->ctc_timestamp, decoder->last_mtc, ctc_rem);
}
@ -1285,6 +1315,12 @@ static void intel_pt_calc_mtc_timestamp(struct intel_pt_decoder *decoder)
mtc = decoder->packet.payload;
if (decoder->mtc_shift > 8 && decoder->fixup_last_mtc) {
decoder->fixup_last_mtc = false;
intel_pt_fixup_last_mtc(mtc, decoder->mtc_shift,
&decoder->last_mtc);
}
if (mtc > decoder->last_mtc)
mtc_delta = mtc - decoder->last_mtc;
else