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Add linux_perf command to turn Linux perf recording on and off.

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This is extremely useful for profiling specific passes.
This commit is contained in:
Robert O'Callahan 2026-01-21 03:18:12 +00:00
parent 125609105d
commit 4f53612725
2 changed files with 97 additions and 0 deletions
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1
passes/cmds/Makefile.inc
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@ -37,6 +37,7 @@ OBJS += passes/cmds/chformal.o
OBJS += passes/cmds/chtype.o
OBJS += passes/cmds/blackbox.o
OBJS += passes/cmds/ltp.o
OBJS += passes/cmds/linux_perf.o
ifeq ($(DISABLE_SPAWN),0)
OBJS += passes/cmds/bugpoint.o
endif

96
passes/cmds/linux_perf.cc Normal file
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@ -0,0 +1,96 @@
/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2014 Claire Xenia Wolf <claire@yosyshq.com>
* Copyright (C) 2014 Johann Glaser <Johann.Glaser@gmx.at>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "kernel/yosys.h"
#include "kernel/log_help.h"
#include <fcntl.h>
#include <stdlib.h>
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
#ifdef __linux__
struct LinuxPerf : public Pass {
LinuxPerf() : Pass("linux_perf", "turn linux perf recording off or on") { }
void help() override
{
log("This pass turns Linux 'perf' profiling on or off, when it has been configured to use control FIFOs.\n");
log("\n");
log("Example shell command line:\n");
log("mkfifo /tmp/perf.fifo /tmp/perf-ack.fifo\n");
log("YOSYS_PERF_CTL=/tmp/perf.fifo YOSYS_PERF_ACK=/tmp/perf-ack.fifo \\\n");
log(" perf record --latency --delay=-1 \\\n");
log(" --control=fifo:/tmp/perf.fifo,/tmp/perf-ack.fifo --call-graph=dwarf ./yosys -dt -p \\\n");
log(" \"read_rtlil design.rtlil; linux_perf on; opt_clean; linux_perf off\"\n");
log("\n");
log(" linux_perf on\n");
log("\n");
log("Start perf recording. YOSYS_PERF_CTL and YOSYS_PERF_ACK must point to Linux perf control FIFOs.\n");
log("\n");
log(" linux_perf off\n");
log("\n");
log("Stop perf recording.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *) override
{
if (args.size() > 2)
cmd_error(args, 2, "Unexpected argument.");
std::string_view ctl_msg;
if (args.size() == 2) {
if (args[1] == "on")
ctl_msg = "enable\n";
else if (args[1] == "off")
ctl_msg = "disable\n";
else
cmd_error(args, 1, "Unexpected argument.");
}
const char *ctl_fifo = std::getenv("YOSYS_PERF_CTL");
if (!ctl_fifo)
log_error("YOSYS_PERF_CTL environment variable not set.");
const char *ack_fifo = std::getenv("YOSYS_PERF_ACK");
if (!ack_fifo)
log_error("YOSYS_PERF_ACK environment variable not set.");
int ctl_fd = open(ctl_fifo, O_WRONLY);
if (ctl_fd < 0)
log_error("Failed to open YOSYS_PERF_CTL.");
int ack_fd = open(ack_fifo, O_RDONLY);
if (ack_fd < 0)
log_error("Failed to open YOSYS_PERF_ACK.");
int result = write(ctl_fd, ctl_msg.data(), ctl_msg.size());
if (result != static_cast<int>(ctl_msg.size()))
log_error("Failed to write to YOSYS_PERF_CTL.");
char buffer[64];
result = read(ack_fd, buffer, sizeof(buffer));
close(ctl_fd);
close(ack_fd);
if (result <= 0)
log_error("Failed to read from YOSYS_PERF_ACK.");
if (strcmp(buffer, "ack\n") != 0)
log_error("YOSYS_PERF_ACK did not return 'ack'.");
}
} LinuxPerf;
#endif
PRIVATE_NAMESPACE_END