From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from picard.linux.it (picard.linux.it [213.254.12.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F3B90C4332F for ; Fri, 4 Nov 2022 12:47:12 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id EB2DD3C8A03 for ; Fri, 4 Nov 2022 13:47:10 +0100 (CET) Received: from in-7.smtp.seeweb.it (in-7.smtp.seeweb.it [217.194.8.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384)) (No client certificate requested) by picard.linux.it (Postfix) with ESMTPS id 8C6F23C0427 for ; Fri, 4 Nov 2022 13:47:00 +0100 (CET) Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by in-7.smtp.seeweb.it (Postfix) with ESMTPS id 43C0D200089 for ; Fri, 4 Nov 2022 13:46:58 +0100 (CET) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 677E521983; Fri, 4 Nov 2022 12:46:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1667566018; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=buBidWB8ddCtKQuR+bEp+140nD47vlydiuR7XBryLwo=; b=ZhtDi5pc9nB7x10tl3iJm5TCRDxjwmruzEl3lReqglAnS5FfRVSIW6pq0aisUvf7yHYSx/ /cLWJTbnobAn8gsGWzXiPxrYF0n5GxCGv8YUbb/YOG/KYUBlzJ0pif8eOJ+GojR9OBwbpI bvl0iTDPTMlSlIHq7LTnFZ/LIyzLMQA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1667566018; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=buBidWB8ddCtKQuR+bEp+140nD47vlydiuR7XBryLwo=; b=kJV9WttDdqqR1RPEHu6oBXXKBEX1OdXQMoqIP0/QAJcFvP2+AFHKtrp23SVoXIflxACNj7 IRIRc617qgfTvqAw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 530AC13216; Fri, 4 Nov 2022 12:46:58 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id tIR7E8IJZWP9cQAAMHmgww (envelope-from ); Fri, 04 Nov 2022 12:46:58 +0000 Message-ID: Date: Fri, 4 Nov 2022 13:46:57 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 To: Andrea Cervesato , ltp@lists.linux.it References: <20221104092411.5446-1-andrea.cervesato@suse.com> Content-Language: en-US From: Martin Doucha In-Reply-To: <20221104092411.5446-1-andrea.cervesato@suse.com> X-Virus-Scanned: clamav-milter 0.102.4 at in-7.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH v1] Correctly handle user time in setitimer01 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: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" Hi, suggestion below. On 04. 11. 22 10:24, Andrea Cervesato via ltp wrote: > Since ITIMER_VIRTUAL and ITIMER_PROF are counting down in user time, we > need to take in consideration CLOCK_MONOTONIC_COARSE resolution. This is > requested by the syscall, since it's considering context switch from > user to kernel mode by using a higher clock resolution. > > Signed-off-by: Andrea Cervesato > --- > .../kernel/syscalls/setitimer/setitimer01.c | 54 +++++++++++-------- > 1 file changed, 33 insertions(+), 21 deletions(-) > > diff --git a/testcases/kernel/syscalls/setitimer/setitimer01.c b/testcases/kernel/syscalls/setitimer/setitimer01.c > index eb62f02c6..5fcae53e8 100644 > --- a/testcases/kernel/syscalls/setitimer/setitimer01.c > +++ b/testcases/kernel/syscalls/setitimer/setitimer01.c > @@ -8,9 +8,16 @@ > /*\ > * [Description] > * > - * Spawn a child and verify that setitimer() syscall passes, and it ends up > + * Spawn a child, verify that setitimer() syscall passes and it ends up > * counting inside expected boundaries. Then verify from the parent that our > * syscall sent the correct signal to the child. > + * > + * Boundaries are choosen accordingly with system clock. In particular, when > + * timer counts down in real time, CLOCK_MONOTONIC resolution has taken into > + * account as our time step. When timer counts down in user time, > + * CLOCK_MONOTONIC_COARSE is used. The reason is that CLOCK_MONOTONIC_COARSE > + * is our system resolution in user space, since it's taking in consideration > + * context switches from user to kernel space. > */ > > #include > @@ -22,7 +29,6 @@ > #include "tst_safe_clocks.h" > > static struct itimerval *value, *ovalue; > -static unsigned long time_step; > > static struct tcase { > int which; > @@ -55,9 +61,31 @@ static void set_setitimer_value(int usec, int o_usec) > static void verify_setitimer(unsigned int i) > { > pid_t pid; > - int status; > - int usec = 3 * time_step; > + struct timespec res; > struct tcase *tc = &tcases[i]; > + int status, usec, time_step, error; > + > + if (tc->which == ITIMER_REAL) > + SAFE_CLOCK_GETRES(CLOCK_MONOTONIC, &res); > + else > + SAFE_CLOCK_GETRES(CLOCK_MONOTONIC_COARSE, &res); > + > + time_step = res.tv_nsec / 1000; > + error = time_step; > + > + if (time_step <= 0) { > + time_step = 1000; > + error = 0; > + } This approach looks like it'll lead to some bad edge cases when 0 < time_step < 1000. It'd be better to keep the original time_step detection and initialize "error" variable like this (and also rename it to "margin"): int jiffy; verify_setitimer() { ... margin = (tc->which == ITIMER_REAL) ? 0 : jiffy; ... } setup() { ... SAFE_CLOCK_GETRES(CLOCK_MONOTONIC_COARSE, &res); jiffy = (res.tv_nsec + 999) / 1000; ... } > + > + usec = 3 * time_step; > + > + tst_res(TINFO, "clock resolution: %luns, " > + "time step: %ius, " > + "counter time: %ius", > + res.tv_nsec, > + time_step, > + usec); > > pid = SAFE_FORK(); > > @@ -76,7 +104,7 @@ static void verify_setitimer(unsigned int i) > ovalue->it_value.tv_sec, > ovalue->it_value.tv_usec); > > - if (ovalue->it_value.tv_sec != 0 || ovalue->it_value.tv_usec > usec) > + if (ovalue->it_value.tv_sec != 0 || ovalue->it_value.tv_usec > usec + error) > tst_res(TFAIL, "Ending counters are out of range"); > > for (;;) > @@ -91,26 +119,10 @@ static void verify_setitimer(unsigned int i) > tst_res(TFAIL, "Child: %s", tst_strstatus(status)); > } > > -static void setup(void) > -{ > - struct timespec res; > - > - SAFE_CLOCK_GETRES(CLOCK_MONOTONIC, &res); > - > - time_step = res.tv_nsec / 1000; > - if (time_step < 10000) > - time_step = 10000; > - > - tst_res(TINFO, "clock resolution: %luns, time step: %luus", > - res.tv_nsec, > - time_step); > -} > - > static struct tst_test test = { > .tcnt = ARRAY_SIZE(tcases), > .forks_child = 1, > .test = verify_setitimer, > - .setup = setup, > .bufs = (struct tst_buffers[]) { > {&value, .size = sizeof(struct itimerval)}, > {&ovalue, .size = sizeof(struct itimerval)}, -- Martin Doucha mdoucha@suse.cz QA Engineer for Software Maintenance SUSE LINUX, s.r.o. CORSO IIa Krizikova 148/34 186 00 Prague 8 Czech Republic -- Mailing list info: https://lists.linux.it/listinfo/ltp