From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH v2 0/4] trace-cmd: Align guest TSC calculation with the kernel
Date: Thu, 14 Oct 2021 18:02:00 +0300 [thread overview]
Message-ID: <20211014150204.2485499-1-tz.stoyanov@gmail.com> (raw)
The formula for calculating guest TSC clock, used in the kernel is:
guest_tsc = tsc-offset + (host_tsc * tsc-scaling-ratio) >> tsc-scaling-ratio-frac-bits
Current trace-cmd implementation does not take into account fraction
bits, when calculating guest clock offset in case of a clock scaling.
Additional logic is added, to use the same formula in trace-cmd. The changes
are backward compatible with trace-cmd 2.9.
The changes are not tested with a kernel that has guest clock scaling enabled.
The goal of the patch set is to extend the time sync option, saved in the
guest trace.dat file, with all needed data used in the kernel for guest TSC
calculations.
v2 changes:
- Use strcmp() instead of strncmp() when searching for KVM debug files.
- Added more comments.
- Code clean ups.
Tzvetomir Stoyanov (VMware) (4):
trace-cmd library: Do not use strncmp() when searching for KVM debug
files
trace-cmd library: Extend host-guest time sync with fraction bits
trace-cmd library: Read and use fraction bits from
TRACECMD_OPTION_TIME_SHIFT
trace-cmd: Dump fraction bits from TRACECMD_OPTION_TIME_SHIFT
.../include/private/trace-cmd-private.h | 4 +-
lib/trace-cmd/include/trace-tsync-local.h | 7 +-
lib/trace-cmd/trace-input.c | 79 +++++++-------
lib/trace-cmd/trace-timesync-kvm.c | 62 +++++++----
lib/trace-cmd/trace-timesync-ptp.c | 4 +-
lib/trace-cmd/trace-timesync.c | 55 ++++++++--
tracecmd/trace-dump.c | 102 +++++++++++++-----
7 files changed, 210 insertions(+), 103 deletions(-)
--
2.31.1
next reply other threads:[~2021-10-14 15:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-14 15:02 Tzvetomir Stoyanov (VMware) [this message]
2021-10-14 15:02 ` [PATCH v2 1/4] trace-cmd library: Do not use strncmp() when searching for KVM debug files Tzvetomir Stoyanov (VMware)
2021-10-14 15:02 ` [PATCH v2 2/4] trace-cmd library: Extend host-guest time sync with fraction bits Tzvetomir Stoyanov (VMware)
2021-10-14 15:02 ` [PATCH v2 3/4] trace-cmd library: Read and use fraction bits from TRACECMD_OPTION_TIME_SHIFT Tzvetomir Stoyanov (VMware)
2021-10-14 15:02 ` [PATCH v2 4/4] trace-cmd: Dump " Tzvetomir Stoyanov (VMware)
2021-11-09 16:07 ` Steven Rostedt
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