Re: [PATCH 1/1] add StartTimeMonotomic, StartTimeBootTime to per pid in /proc
The process starttime is useful for a variety of things, like figuring out creation ordering of processes. Or it is useful to detect PID reuses in a somewhat reliable way. OK, maybe. Changelog should have said so. Yeah, Dan was also too lazy to explain the need, and had like 3 typoes in the inadequate changelog he had. Does not inspire confidence. Now please all untwist your panties and try and submit a proper patch. Resubmitted with more explanation (and less typos). If you feel that having both CLOCK_MONOTONIC and CLOCK_BOOTTIME is really a sticking point I'd be ok to remove one as long as the other made it through, as one is much better than none. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] add StartTimeMonotomic, StartTimeBootTime to per pid in /proc
On Fri, 24.01.14 12:32, Peter Zijlstra (pet...@infradead.org) wrote: > > The process starttime is useful for a variety of things, like figuring > > out creation ordering of processes. Or it is useful to detect PID > > reuses in a somewhat reliable way. > > OK, maybe. Changelog should have said so. > > > It is useful information to show the admin in "ps". > > Does the one jiffy rounding really matter there? I doubt it, ps > typically shows in second granularity. Well, it's just annoying. Much of userspace uses CLOCK_MONOTONIC throughout all the local timestamping needs these days, however the jiffy rounding and the fact that "starttime" is based on CLOCK_BOOTTIME makes it hard to compare process timestamps currently with other timestamps... > > Profilers like "bootchart" can use this information to > > plot when precisely specific process got started. From the outside it is > > often useful to see for how long a specific process has already been > > running, for accounting needs, and so on. > > Profilers have far better interfaces than /proc to get information > from. That is true, but note that at least on Fedora taskstats and thing are actually disabled these days in the kernel, since they slow things down too much. The /proc interface is certainly much nicer there, since it relies on a the timestamping the kernel does anyway... > > Note that Dan's patch doesn't add any new timestamp logic to the kernel, > > it just exposes the existing timestamps in a way to userspace that is > > more in line with the rest of timestamps exposed. > > Yeah, Dan was also too lazy to explain the need, and had like 3 typoes > in the inadequate changelog he had. > > He also fails to explain why he needs the timestamp twice, as do you for > that matter. Well, I am mostly interesting int the monotonic timestamp. But given that the kernel keeps the boottime clock value as well, and already exposes it in a skewed way to userspace it looked like a natural choice to also expose that time in a clean way, while we are it... Lennart -- Lennart Poettering, Red Hat -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] add StartTimeMonotomic, StartTimeBootTime to per pid in /proc
On Fri, Jan 24, 2014 at 11:20:38AM +0100, Lennart Poettering wrote: > On Wed, 22.01.14 16:53, Peter Zijlstra (pet...@infradead.org) wrote: > > > > > On Tue, Jan 21, 2014 at 07:10:04AM -0800, Dan Ballard wrote: > > > starttime in /proc/$PID/stat is inaccurate by "clock tick" granularity. > > > The kernel keeps better track os this exposes that in /prod/$PID/status > > > as StartTimeMonotonic and StartTimeBootTime > > > > Why? > > Well, the canonical way to expose clocks to userspace these days is with > CLOCK_MONOTONIC, CLOCK_BOOTTIME, and so on. The starttime is currently > exposed in a way that is made inaccurate by the clock tick in > /proc/$PID/stat. Dan's patch simply unfucks that interface. That's actually factually incorrect. The start_time in task_stat is the exact same as used by Dan, its just that task_stat() decides to wreck it before printing it. Doesn't have anything to do with the actual clock tick. > The process starttime is useful for a variety of things, like figuring > out creation ordering of processes. Or it is useful to detect PID > reuses in a somewhat reliable way. OK, maybe. Changelog should have said so. > It is useful information to show the admin in "ps". Does the one jiffy rounding really matter there? I doubt it, ps typically shows in second granularity. > Profilers like "bootchart" can use this information to > plot when precisely specific process got started. From the outside it is > often useful to see for how long a specific process has already been > running, for accounting needs, and so on. Profilers have far better interfaces than /proc to get information from. > Note that Dan's patch doesn't add any new timestamp logic to the kernel, > it just exposes the existing timestamps in a way to userspace that is > more in line with the rest of timestamps exposed. Yeah, Dan was also too lazy to explain the need, and had like 3 typoes in the inadequate changelog he had. He also fails to explain why he needs the timestamp twice, as do you for that matter. Does not inspire confidence. Now please all untwist your panties and try and submit a proper patch. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] add StartTimeMonotomic, StartTimeBootTime to per pid in /proc
On Wed, 22.01.14 16:53, Peter Zijlstra (pet...@infradead.org) wrote: > > On Tue, Jan 21, 2014 at 07:10:04AM -0800, Dan Ballard wrote: > > starttime in /proc/$PID/stat is inaccurate by "clock tick" granularity. > > The kernel keeps better track os this exposes that in /prod/$PID/status > > as StartTimeMonotonic and StartTimeBootTime > > Why? Well, the canonical way to expose clocks to userspace these days is with CLOCK_MONOTONIC, CLOCK_BOOTTIME, and so on. The starttime is currently exposed in a way that is made inaccurate by the clock tick in /proc/$PID/stat. Dan's patch simply unfucks that interface. The process starttime is useful for a variety of things, like figuring out creation ordering of processes. Or it is useful to detect PID reuses in a somewhat reliable way. It is useful information to show the admin in "ps". Profilers like "bootchart" can use this information to plot when precisely specific process got started. From the outside it is often useful to see for how long a specific process has already been running, for accounting needs, and so on. Note that Dan's patch doesn't add any new timestamp logic to the kernel, it just exposes the existing timestamps in a way to userspace that is more in line with the rest of timestamps exposed. Lennart -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] add StartTimeMonotomic, StartTimeBootTime to per pid in /proc
On Thu, Jan 23, 2014 at 06:52:03AM -0800, Dan Ballard wrote: > On request of Lennart Poettering for the Linux plumbers. That's not an answer, so NAK then. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] add StartTimeMonotomic, StartTimeBootTime to per pid in /proc
On request of Lennart Poettering for the Linux plumbers. On 14-01-22 07:53 AM, Peter Zijlstra wrote: On Tue, Jan 21, 2014 at 07:10:04AM -0800, Dan Ballard wrote: starttime in /proc/$PID/stat is inaccurate by "clock tick" granularity. The kernel keeps better track os this exposes that in /prod/$PID/status as StartTimeMonotonic and StartTimeBootTime Why? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] add StartTimeMonotomic, StartTimeBootTime to per pid in /proc
On Tue, Jan 21, 2014 at 07:10:04AM -0800, Dan Ballard wrote: > starttime in /proc/$PID/stat is inaccurate by "clock tick" granularity. > The kernel keeps better track os this exposes that in /prod/$PID/status > as StartTimeMonotonic and StartTimeBootTime > Why? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 1/1] add StartTimeMonotomic, StartTimeBootTime to per pid in /proc
starttime in /proc/$PID/stat is inaccurate by "clock tick" granularity. The kernel keeps better track os this exposes that in /prod/$PID/status as StartTimeMonotonic and StartTimeBootTime Signed-off-by: Dan Ballard --- Documentation/filesystems/proc.txt |6 +- fs/proc/array.c|8 ++-- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 22d89aa3..6ed8001 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -158,6 +158,8 @@ read the file /proc/PID/status: TracerPid: 0(2.4) Uid:501 501 501 501 Gid:100 100 100 100 + StartTimeMonotonic: 3766799643 + StartTimeBootTime: 3766799643 FDSize: 256 Groups: 100 14 16 VmPeak: 5004 kB @@ -202,7 +204,7 @@ asynchronous manner and the vaule may not be very precise. To see a precise snapshot of a moment, you can see /proc//smaps file and scan page table. It's slow but very precise. -Table 1-2: Contents of the status files (as of 2.6.30-rc7) +Table 1-2: Contents of the status files (as of 3.13.0-rc3) .. Field Content Namefilename of the executable @@ -215,6 +217,8 @@ Table 1-2: Contents of the status files (as of 2.6.30-rc7) TracerPid PID of process tracing this process (0 if not) Uid Real, effective, saved set, and file system UIDs Gid Real, effective, saved set, and file system GIDs + StartTimeMonotonic Start time of process in nsec from CLOCK_MONOTONIC + StartTimeBootTime Start time of process in nsec from CLOCK_BOOTTIME FDSize number of file descriptor slots currently allocated Groups supplementary group list VmPeak peak virtual memory size diff --git a/fs/proc/array.c b/fs/proc/array.c index 1bd2077..34f4761 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -188,7 +188,9 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, "PPid:\t%d\n" "TracerPid:\t%d\n" "Uid:\t%d\t%d\t%d\t%d\n" - "Gid:\t%d\t%d\t%d\t%d\n", + "Gid:\t%d\t%d\t%d\t%d\n" + "StartTimeMonotonic:\t%lld\n" + "StartTimeBootTime:\t%lld\n", get_task_state(p), task_tgid_nr_ns(p, ns), task_numa_group_id(p), @@ -201,7 +203,9 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, from_kgid_munged(user_ns, cred->gid), from_kgid_munged(user_ns, cred->egid), from_kgid_munged(user_ns, cred->sgid), - from_kgid_munged(user_ns, cred->fsgid)); + from_kgid_munged(user_ns, cred->fsgid), + timespec_to_ns(&p->start_time), + timespec_to_ns(&p->real_start_time)); task_lock(p); if (p->files) -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
