Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757146AbYF0IHx (ORCPT ); Fri, 27 Jun 2008 04:07:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753332AbYF0IHY (ORCPT ); Fri, 27 Jun 2008 04:07:24 -0400 Received: from wx-out-0506.google.com ([66.249.82.229]:29924 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756568AbYF0IG5 (ORCPT ); Fri, 27 Jun 2008 04:06:57 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=gC8HM/PL+eU9z3QUWN2jMUhZO7dEG5D6xHAfNUWvmzZ9OXRGAoVtp4UTmez4N9s0H7 uO7PNYK3ep1FNdYcD4z1DFEF+OGOLSZnXnO0GbKcSU2AfeQFuQsBOLpNycPzUnsgY/6S /iEB8i359dClTYQxCR7vn7ugAvrlmTeDySN/I= Message-ID: Date: Fri, 27 Jun 2008 10:06:56 +0200 From: "Michael Kerrisk" To: "Oleg Nesterov" Subject: Re: [patch] make siginfo_t si_utime + si_sstime report times in USER_HZ, not HZ Cc: "Thomas Gleixner" , lkml , "Andrew Morton" , "Bart Van Assche" , "Roland McGrath" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080625153806.GA499@tv-sign.ru> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7549 Lines: 250 On Thu, Jun 26, 2008 at 5:09 PM, Michael Kerrisk wrote: > On Wed, Jun 25, 2008 at 5:38 PM, Oleg Nesterov wrote: >> On 06/25, Michael Kerrisk wrote: >>> >>> --- /home/mtk/ARCHIVE/KERNEL/linux-2.6.26-rc7/kernel/signal.c.orig 2008-06-24 >>> 16:20:39.000000000 +0200 >>> +++ /home/mtk/ARCHIVE/KERNEL/linux-2.6.26-rc7/kernel/signal.c 2008-06-24 >>> 16:22:17.000000000 +0200 >>> @@ -1379,10 +1379,9 @@ >>> >>> info.si_uid = tsk->uid; >>> >>> - /* FIXME: find out whether or not this is supposed to be c*time. */ >>> - info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime, >>> + info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime, >>> tsk->signal->utime)); >>> - info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime, >>> + info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime, >>> tsk->signal->stime)); >>> >>> info.si_status = tsk->exit_code & 0x7f; >>> @@ -1450,9 +1449,8 @@ >>> >>> info.si_uid = tsk->uid; >>> >>> - /* FIXME: find out whether or not this is supposed to be c*time. */ >>> - info.si_utime = cputime_to_jiffies(tsk->utime); >>> - info.si_stime = cputime_to_jiffies(tsk->stime); >>> + info.si_utime = cputime_to_clock_t(tsk->utime); >>> + info.si_stime = cputime_to_clock_t(tsk->stime); >>> >>> info.si_code = why; >>> switch (why) { >> >> This looks like the obviously good fix to me. > > Tested now, and it does what I expect. > >> The patch also deletes the comment about signal_struct->cXtime, >> this also looks right: why should we use cutime/cstime ? > > Hmmm -- maybe I was wrong to delete that comment. I think the point > of the comment was: should the time returned vie these fields of the > signinfo structure also include the times for (grand)children of the > process that had terminated and been wait()ed for. My first take on > that was "no". But now I'm not 100% sure. A quick test on Solaris 8 > suggests that these fields *do* include the times of waited for > children. (None of this is specified in POSIX.1, which doesn't > specify si_utime and si_stime.) I've not yet tested FreeBSD (not sure > if it supports these fields or not). So, FreeBSD doesn't implement these fields. A more extensive test (see below) on Solaris (8) shows that it does indeed include the times of waited-for children in the si_utime and si_stime fields. I'm not sure if we should emulate that behavior or not - it'd be easy enough to do so of course. Thoughts, anyone? Cheers, Michael Test ==== (If anyone has access to Tru64 or Irix, I'd be interested to see results from the test program below.) Using the test program below allows us to see the difference if the child doesn't wait on it's child versus if it does wait. # Child creates (grand)child that burns 1 second of CPU # Child burns 2 seconds of CPU, and waits for 4 seconds # Child does not wait on (grand)child $ ./a.out 2 4 1 Child 17838 about to burn 1 secs Child 17838 done Finished burn Finished sleep waited for 0 children SIGCHLD si_status=0x0; si_utime=37 si_stime=164 # Child creates (grand)child that burns 1 second of CPU # Child burns 2 seconds of CPU, and waits for 4 seconds # Child waits on (grand)child $ ./a.out 2 4 1w Child 17841 about to burn 1 secs Child 17841 done Finished burn Finished sleep About to wait for child 3 (1w), PID 17841 waited for 1 children SIGCHLD si_status=0x0; si_utime=59 si_stime=243 ================== /* sigchld_siginfo_time_test.c Copyright 2008, Linux Foundation Author: Michael Kerrisk Licensed under GPLv2 or later */ #include #include #include #include #include #include #include #include #include #include #define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \ } while (0) #define usageErr(msg, progName) \ do { fprintf(stderr, "Usage: "); \ fprintf(stderr, msg, progName); \ exit(EXIT_FAILURE); } while (0) static void handler(int sig, siginfo_t *siginfo, void *arg) { printf("SIGCHLD si_status=0x%x; ", (unsigned int) siginfo->si_status); printf("si_utime=%ld si_stime=%ld\n", siginfo->si_utime, siginfo->si_stime); } /* handler */ static void burn(int nsecs) { struct rusage start, curr; float t; if (getrusage(RUSAGE_SELF, &start) == -1) errExit("getrusage"); for (;;) { if (getrusage(RUSAGE_SELF, &curr) == -1) errExit("getrusage"); t = (curr.ru_utime.tv_sec - start.ru_utime.tv_sec) * 1000000 + (curr.ru_utime.tv_usec - start.ru_utime.tv_usec) + (curr.ru_stime.tv_sec - start.ru_stime.tv_sec) * 1000000 + (curr.ru_stime.tv_usec - start.ru_stime.tv_usec); if (t > nsecs * 1000000) break; } } /* burn */ static void doChild(int argc, char *argv[]) { int cn, waited, rtime; pid_t *childList; char *ep; if (signal(SIGCHLD, SIG_DFL) == SIG_ERR) errExit("signal"); childList = calloc(argc, sizeof(pid_t)); if (childList == NULL) errExit("calloc"); for (cn = 3; cn < argc; cn++) { rtime = strtol(argv[cn], &ep, 0); childList[cn] = fork(); if (childList[cn] == -1) errExit("fork"); if (childList[cn] == 0) { printf("Child %ld about to burn %d secs\n", (long) getpid(), rtime); burn(rtime); printf("Child %ld done\n", (long) getpid()); exit(EXIT_SUCCESS); } else { if (*ep == '\0') childList[cn] = -childList[cn]; /* Don't waitpid() */ } } /* Burn some CPU time ourselves */ burn(atoi(argv[1])); printf("Finished burn\n"); /* Optionally sleep for a while, so as to allow children that we don't wait for to terminate */ sleep(atoi(argv[2])); printf("Finished sleep\n"); /* Wait for children */ waited = 0; for (cn = 3; cn < argc; cn++) { if (childList[cn] > 0) { printf("About to wait for child %d (%s), PID %ld\n", cn, argv[cn], (long) childList[cn]); if (waitpid(childList[cn], NULL, 0) == -1) errExit("waitpid"); waited++; } } printf("waited for %d children\n", waited); } /* doChild */ int main(int argc, char *argv[]) { struct sigaction sa; pid_t childPid; if (argc < 4 || strcmp(argv[1], "--help") == 0) usageErr("%s " "[w]...\n", argv[0]); sa.sa_flags = SA_SIGINFO; sa.sa_sigaction = handler; sigemptyset(&sa.sa_mask); if (sigaction(SIGCHLD, &sa, NULL) == -1) errExit("sigaction"); childPid = fork(); if (childPid == -1) errExit("fork"); if (childPid == 0) { doChild(argc, argv); exit(EXIT_SUCCESS); } pause(); /* Wait for SIGCHLD */ exit(EXIT_SUCCESS); } /* main */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/