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Wed, 12 Jun 2024 12:21:22 +0000 Date: Wed, 12 Jun 2024 14:21:20 +0200 From: Petr Vorel To: Cyril Hrubis Message-ID: <20240612122120.GA118569@pevik> References: <20240612112311.10334-1-chrubis@suse.cz> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240612112311.10334-1-chrubis@suse.cz> X-Rspamd-Queue-Id: 0AE653440F X-Spamd-Result: default: False [-3.71 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; HAS_REPLYTO(0.30)[pvorel@suse.cz]; NEURAL_HAM_SHORT(-0.20)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; MISSING_XM_UA(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; REPLYTO_EQ_FROM(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RCVD_TLS_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.cz:+] X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Virus-Scanned: clamav-milter 1.0.3 at in-4.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH v2] sched: starvation: Autocallibrate the timeout X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Petr Vorel Cc: Steve , ltp@lists.linux.it Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" Hi Cyril, > Instead of hardcoding the values we attempt to measure the CPU speed and > set the timeout accordingly. Given that the difference in the duration > of the test when the kernel is buggy is about 30x we do not have to have > a precise callibration, just very rough estimate if we are running on a > server or small ARM board would suffice. > So we attempt to measure how long does a bussy loop take and base the s/bussy/busy/ > default timeout on that. On x86_64 CPUs the resulting timeout is about > double of the value of the actual test runtime and works fine, but we > need to make sure that the coeficient we divide the result from > callibrate works for small boards too. So please run the test on as many > machines as you can and report if we need to make the dividor smaller or > not. This looks much better: ppc64le has Timeout per run is 0h 00m 30s (1m 10s runtime), others (x68_64, s390x, aarch64) have ~ 1 min or less. Tested-by: Petr Vorel ... > +static int callibrate(void) > +{ > + int i; > + struct timespec start, stop; > + long long diff; > + > + for (i = 0; i < CALLIBRATE_LOOPS; i++) { > + __asm__ __volatile__ ("" : "+g" (i) : :); > + } > + > + SAFE_CLOCK_GETTIME(CLOCK_MONOTONIC_RAW, &start); > + > + for (i = 0; i < CALLIBRATE_LOOPS; i++) { > + __asm__ __volatile__ ("" : "+g" (i) : :); > + } > + > + SAFE_CLOCK_GETTIME(CLOCK_MONOTONIC_RAW, &stop); > + > + diff = tst_timespec_diff_us(stop, start); > + > + tst_res(TINFO, "CPU did %i loops in %llius", CALLIBRATE_LOOPS, diff); > + > + return diff; > +} > static int wait_for_pid(pid_t pid) > { > @@ -59,8 +88,11 @@ static void setup(void) > if (tst_parse_long(str_loop, &loop, 1, LONG_MAX)) > tst_brk(TBROK, "Invalid number of loop number '%s'", str_loop); > - if (tst_parse_int(str_timeout, &timeout, 1, INT_MAX)) > + if (tst_parse_int(str_timeout, &timeout, 1, INT_MAX)) { nit: {} brackets are not needed. Reviewed-by: Petr Vorel Kind regards, Petr > tst_brk(TBROK, "Invalid number of timeout '%s'", str_timeout); > + } else { > + timeout = callibrate() / 1000; > + } > tst_set_max_runtime(timeout); > } -- Mailing list info: https://lists.linux.it/listinfo/ltp