On Thu, 1 Sep 2022 17:09:56 +0200
Nico Boehr <nrb@xxxxxxxxxxxxx> wrote:
> Add a test to measure the execution time of several instructions. This
> can be helpful in finding performance regressions in hypervisor code.
>
> All tests are currently reported as PASS, since the baseline for their
> execution time depends on the respective environment and since needs to
> be determined on a case-by-case basis.
>
> Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
> ---
> s390x/Makefile | 1 +
> s390x/exittime.c | 255 ++++++++++++++++++++++++++++++++++++++++++++
> s390x/unittests.cfg | 4 +
> 3 files changed, 260 insertions(+)
> create mode 100644 s390x/exittime.c
>
> diff --git a/s390x/Makefile b/s390x/Makefile
> index efd5e0c13102..5dcac244767f 100644
> --- a/s390x/Makefile
> +++ b/s390x/Makefile
> @@ -34,6 +34,7 @@ tests += $(TEST_DIR)/migration.elf
> tests += $(TEST_DIR)/pv-attest.elf
> tests += $(TEST_DIR)/migration-cmm.elf
> tests += $(TEST_DIR)/migration-skey.elf
> +tests += $(TEST_DIR)/exittime.elf
>
> pv-tests += $(TEST_DIR)/pv-diags.elf
>
> diff --git a/s390x/exittime.c b/s390x/exittime.c
> new file mode 100644
> index 000000000000..543c82ff3906
> --- /dev/null
> +++ b/s390x/exittime.c
> @@ -0,0 +1,255 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Measure run time of various instructions. Can be used to find runtime
> + * regressions of instructions which cause exits.
> + *
> + * Copyright IBM Corp. 2022
> + *
> + * Authors:
> + * Nico Boehr <nrb@xxxxxxxxxxxxx>
> + */
> +#include <libcflat.h>
> +#include <smp.h>
> +#include <sclp.h>
> +#include <asm/time.h>
> +#include <asm/sigp.h>
> +#include <asm/interrupt.h>
> +#include <asm/page.h>
> +
> +char pagebuf[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
> +
> +static void test_sigp_sense_running(long destcpu)
> +{
> + smp_sigp(destcpu, SIGP_SENSE_RUNNING, 0, NULL);
> +}
> +
> +static void test_nop(long ignore)
> +{
> + /* nops don't trap into the hypervisor, so let's test them for reference */
> + asm volatile("nop" : : : "memory");
> +}
> +
> +static void test_diag9c(long destcpu)
> +{
> + asm volatile("diag %[destcpu],0,0x9c"
> + :
> + : [destcpu] "d" (destcpu)
> + :
here you leave some unused :
> + );
> +}
> +
> +static long setup_get_this_cpuaddr(long ignore)
> +{
> + return stap();
> +}
> +
> +static void test_diag44(long ignore)
> +{
> + asm volatile("diag 0,0,0x44");
> +}
> +
> +static void test_stnsm(long ignore)
> +{
> + int out;
> +
> + asm volatile(
> + "stnsm %[out],0xff"
> + : [out] "=Q" (out)
> + :
here too, but you are using only 2
> + );
> +}
> +
> +static void test_stosm(long ignore)
> +{
> + int out;
> +
> + asm volatile(
> + "stosm %[out],0"
> + : [out] "=Q" (out)
> + :
> + );
> +}
> +
> +static long setup_ssm(long ignore)
> +{
> + long system_mask = 0;
> +
> + asm volatile(
> + "stosm %[system_mask],0"
> + : [system_mask] "=Q" (system_mask)
> + :
> + :
> + );
> +
> + return system_mask;
> +}
> +
> +static void test_ssm(long old_system_mask)
> +{
> + asm volatile(
> + "ssm %[old_system_mask]"
> + :
> + : [old_system_mask] "Q" (old_system_mask)
> + :
> + );
> +}
> +
> +static long setup_lctl4(long ignore)
> +{
> + long ctl4_orig = 0;
> +
> + asm volatile(
> + "stctg 4,4,%[ctl4_orig]"
> + : [ctl4_orig] "=S" (ctl4_orig)
> + :
> + :
> + );
> +
> + return ctl4_orig;
> +}
> +
> +static void test_lctl4(long ctl4_orig)
> +{
> + asm volatile(
> + "lctlg 4,4,%[ctl4_orig]"
> + :
> + : [ctl4_orig] "S" (ctl4_orig)
> + :
> + );
> +}
> +
> +static void test_stpx(long ignore)
> +{
> + unsigned int prefix;
> +
> + asm volatile(
> + "stpx %[prefix]"
> + : [prefix] "=Q" (prefix)
here you are only using the : you actually need
> + );
> +}
> +
> +static void test_stfl(long ignore)
> +{
> + asm volatile(
> + "stfl 0" : : : "memory"
> + );
> +}
> +
> +static void test_epsw(long ignore)
> +{
> + long r1, r2;
> +
> + asm volatile(
> + "epsw %[r1], %[r2]"
> + : [r1] "=d" (r1), [r2] "=d" (r2)
> + :
> + :
> + );
> +}
> +
> +static void test_illegal(long ignore)
> +{
> + expect_pgm_int();
> + asm volatile(
> + ".word 0"
> + :
> + :
> + :
here none are needed
> + );
> + clear_pgm_int();
> +}
decide how you want to do for the : and then do it uniformly.
either you always put all three : (except when none are needed), or you
always only put as many as needed, without empty trailing ones.
> +
> +static long setup_servc(long arg)
> +{
> + memset(pagebuf, 0, PAGE_SIZE);
> + return arg;
> +}
> +
> +static void test_servc(long ignore)
> +{
> + SCCB *sccb = (SCCB *) pagebuf;
> +
> + sccb->h.length = 8;
> + servc(0, (unsigned long) sccb);
> +}
> +
> +static void test_stsi(long fc)
> +{
> + stsi(pagebuf, fc, 2, 2);
> +}
> +
> +struct test {
> + const char *name;
> + /*
> + * When non-null, will be called once before running the test loop.
> + * Its return value will be given as argument to testfunc.
> + */
> + long (*setupfunc)(long arg);
> + void (*testfunc)(long arg);
> + long arg;
> + long iters;
> +} const exittime_tests[] = {
> + {"nop", NULL, test_nop, 0, 200000 },
> + {"sigp sense running(0)", NULL, test_sigp_sense_running, 0, 20000 },
> + {"sigp sense running(1)", NULL, test_sigp_sense_running, 1, 20000 },
> + {"diag9c(self)", setup_get_this_cpuaddr, test_diag9c, 0, 2000 },
> + {"diag9c(0)", NULL, test_diag9c, 0, 2000 },
> + {"diag9c(1)", NULL, test_diag9c, 1, 2000 },
> + {"diag44", NULL, test_diag44, 0, 2000 },
> + {"stnsm", NULL, test_stnsm, 0, 200000 },
> + {"stosm", NULL, test_stosm, 0, 200000 },
> + {"ssm", setup_ssm, test_ssm, 0, 200000 },
> + {"lctl4", setup_lctl4, test_lctl4, 0, 20000 },
> + {"stpx", NULL, test_stpx, 0, 2000 },
> + {"stfl", NULL, test_stfl, 0, 2000 },
> + {"epsw", NULL, test_epsw, 0, 20000 },
> + {"illegal", NULL, test_illegal, 0, 2000 },
> + {"servc", setup_servc, test_servc, 0, 2000 },
> + {"stsi122", NULL, test_stsi, 1, 200 },
> + {"stsi222", NULL, test_stsi, 2, 200 },
> + {"stsi322", NULL, test_stsi, 3, 200 },
> +};
> +
> +static uint64_t tod_to_us(uint64_t tod)
> +{
> + return tod >> STCK_SHIFT_US;
> +}
> +
> +int main(void)
> +{
> + int i, j, k, testfunc_arg;
> + const int outer_iters = 100;
> + struct test const *current_test;
> + uint64_t start, end, elapsed, worst, best, total;
> +
> + report_prefix_push("exittime");
> + report_pass("reporting total/best/worst of %d outer iterations", outer_iters);
> +
> + for (i = 0; i < ARRAY_SIZE(exittime_tests); i++) {
> + current_test = &exittime_tests[i];
> + total = 0;
> + worst = 0;
> + best = -1;
> + report_prefix_pushf("%s", current_test->name);
> +
> + testfunc_arg = current_test->arg;
> + if (current_test->setupfunc)
> + testfunc_arg = current_test->setupfunc(testfunc_arg);
> +
> + for (j = 0; j < outer_iters; j++) {
> + start = get_clock_fast();
> + for (k = 0; k < current_test->iters; k++)
> + current_test->testfunc(testfunc_arg);
> + end = get_clock_fast();
> + elapsed = end - start;
> + best = MIN(best, elapsed);
> + worst = MAX(worst, elapsed);
> + total += elapsed;
> + }
> + report_pass("iters/total/best/worst %lu/%lu/%lu/%lu us", current_test->iters, tod_to_us(total), tod_to_us(best), tod_to_us(worst));
perhaps it would not be a bad idea to also print the average and the
standard deviation (σ)
> + report_prefix_pop();
> + }
> +
> + report_prefix_pop();
> + return report_summary();
> +}
> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
> index f7b1fc3dbca1..c11d1d987c82 100644
> --- a/s390x/unittests.cfg
> +++ b/s390x/unittests.cfg
> @@ -185,3 +185,7 @@ groups = migration
> [migration-skey]
> file = migration-skey.elf
> groups = migration
> +
> +[exittime]
> +file = exittime.elf
> +smp = 2
