Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261798AbTFCWuZ (ORCPT ); Tue, 3 Jun 2003 18:50:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261807AbTFCWuZ (ORCPT ); Tue, 3 Jun 2003 18:50:25 -0400 Received: from e35.co.us.ibm.com ([32.97.110.133]:57085 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S261798AbTFCWuW (ORCPT ); Tue, 3 Jun 2003 18:50:22 -0400 Subject: [RFC][PATCH] linux-2.5.70_btime-fix_A0 From: john stultz To: lkml Cc: h.lambermont@aramiska.net Content-Type: text/plain Organization: Message-Id: <1054681259.32091.783.camel@w-jstultz2.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.4 Date: 03 Jun 2003 16:00:59 -0700 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1916 Lines: 72 All, Since jiffies didn't necessarily start incrementing at a second boundary, jiffies/HZ doesn't increment at the same moment as xtime.tv_sec. This causes one second wobbles in the calculation of btime (xtime.tv_sec - jiffies/HZ). This fix increases the precision of the calculation so the usec component of xtime is used as well. Additionally it fixes some of the non-atomic reading of time values. This is a fix for bugme bug #764. http://bugme.osdl.org/show_bug.cgi?id=764 Let me know if you have any comments thanks -john --- 1.77/fs/proc/proc_misc.c Sun May 25 14:08:09 2003 +++ edited/fs/proc/proc_misc.c Tue Jun 3 15:52:41 2003 @@ -378,8 +378,22 @@ { int i, len; extern unsigned long total_forks; - u64 jif = get_jiffies_64() - INITIAL_JIFFIES; + u64 jif; unsigned int sum = 0, user = 0, nice = 0, system = 0, idle = 0, iowait = 0; + struct timeval now; + unsigned long seq; + + /* Atomically read jiffies and time of day */ + do { + seq = read_seqbegin(&xtime_lock); + + jif = get_jiffies_64() - INITIAL_JIFFIES; + do_gettimeofday(&now); + } while (read_seqretry(&xtime_lock, seq)); + + /* calc # of seconds since boot time */ + jif = ((u64)now.tv_sec * HZ) + (now.tv_usec/(1000000/HZ)) - jif; + do_div(jif, HZ); for (i = 0 ; i < NR_CPUS; i++) { int j; @@ -419,7 +433,6 @@ len += sprintf(page + len, " %u", kstat_irqs(i)); #endif - do_div(jif, HZ); len += sprintf(page + len, "\nctxt %lu\n" "btime %lu\n" @@ -427,7 +440,7 @@ "procs_running %lu\n" "procs_blocked %lu\n", nr_context_switches(), - xtime.tv_sec - (unsigned long) jif, + (unsigned long)jif, total_forks, nr_running(), nr_iowait()); - 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/