From: Oleg Nesterov <oleg@redhat.com> To: Andrew Vagin <avagin@gmail.com> Cc: Andrey Vagin <avagin@openvz.org>, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Cyrill Gorcunov <gorcunov@openvz.org>, Pavel Emelyanov <xemul@parallels.com>, Roger Luethi <rl@hellgate.ch>, Arnd Bergmann <arnd@arndb.de>, Arnaldo Carvalho de Melo <acme@kernel.org>, David Ahern <dsahern@gmail.com>, Andy Lutomirski <luto@amacapital.net>, Pavel Odintsov <pavel.odintsov@gmail.com> Subject: Re: [PATCH 08/24] proc: pick out a function to iterate task children Date: Sat, 18 Jul 2015 23:22:23 +0200 [thread overview] Message-ID: <20150718212223.GA10240@redhat.com> (raw) In-Reply-To: <20150717155728.GB6685@odin.com> On 07/17, Andrew Vagin wrote: > > On Tue, Jul 14, 2015 at 08:02:35PM +0200, Oleg Nesterov wrote: > > On 07/06, Andrey Vagin wrote: > > > > > > -static struct pid * > > > -get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos) > > > +static struct task_struct * > > > +task_next_child(struct task_struct *parent, struct task_struct *prev, unsigned int pos) > > > { > > > > I won't really argue, just a question... > > > > So this patch changes it to accept/return task_struct rather pid. Why? > > it is better to get/put "struct pid" only, not the whole task_struct. > > > > If another caller want task_struct, the necessary conversion is simple. > > Another caller wants task_struct. > > Currently this function receives pid and converts it into task_struct, then > gets the next child and returns its pid. Exactly because we try to avoid get_task_struct() if possible. > So I try to avoid extra > conversion in task_diag code. Which is simple. And perhaps even iter->task can actually be iter->pid. But as I said I won't really argue. And just in case, I personally think this series makes sense, although I can't review the netlink interface. Oleg.
WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> To: Andrew Vagin <avagin-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Cc: Andrey Vagin <avagin-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Cyrill Gorcunov <gorcunov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>, Pavel Emelyanov <xemul-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>, Roger Luethi <rl-7uj+XXdSDtwfv37vnLkPlQ@public.gmane.org>, Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>, Arnaldo Carvalho de Melo <acme-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, David Ahern <dsahern-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, Pavel Odintsov <pavel.odintsov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Subject: Re: [PATCH 08/24] proc: pick out a function to iterate task children Date: Sat, 18 Jul 2015 23:22:23 +0200 [thread overview] Message-ID: <20150718212223.GA10240@redhat.com> (raw) In-Reply-To: <20150717155728.GB6685-wo1vFcy6AUs@public.gmane.org> On 07/17, Andrew Vagin wrote: > > On Tue, Jul 14, 2015 at 08:02:35PM +0200, Oleg Nesterov wrote: > > On 07/06, Andrey Vagin wrote: > > > > > > -static struct pid * > > > -get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos) > > > +static struct task_struct * > > > +task_next_child(struct task_struct *parent, struct task_struct *prev, unsigned int pos) > > > { > > > > I won't really argue, just a question... > > > > So this patch changes it to accept/return task_struct rather pid. Why? > > it is better to get/put "struct pid" only, not the whole task_struct. > > > > If another caller want task_struct, the necessary conversion is simple. > > Another caller wants task_struct. > > Currently this function receives pid and converts it into task_struct, then > gets the next child and returns its pid. Exactly because we try to avoid get_task_struct() if possible. > So I try to avoid extra > conversion in task_diag code. Which is simple. And perhaps even iter->task can actually be iter->pid. But as I said I won't really argue. And just in case, I personally think this series makes sense, although I can't review the netlink interface. Oleg.
next prev parent reply other threads:[~2015-07-18 21:24 UTC|newest] Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-07-06 8:47 [PATCH 0/24] kernel: add a netlink interface to get information about processes (v2) Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 01/24] kernel: define taststats commands in the one place Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 02/24] kernel: add a netlink interface to get information about tasks (v2) Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 03/24] kernel: make taskstats available from all net namespaces Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 04/24] kernel: move next_tgid from fs/proc Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 05/24] task_diag: add ability to get information about all tasks Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 06/24] task_diag: add ability to split per-task data on a few netlink messages Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 07/24] task_diag: add a new group to get process credentials Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 08/24] proc: pick out a function to iterate task children Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-14 18:02 ` Oleg Nesterov 2015-07-14 18:02 ` Oleg Nesterov 2015-07-17 15:57 ` Andrew Vagin 2015-07-17 15:57 ` Andrew Vagin 2015-07-18 21:22 ` Oleg Nesterov [this message] 2015-07-18 21:22 ` Oleg Nesterov 2015-07-06 8:47 ` [PATCH 09/24] proc: move task_next_child() from fs/proc Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 10/24] task_diag: add ability to dump children (v2) Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 11/24] task_diag: add a new group to get task statistics Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 12/24] task_diag: add a new group to get tasks memory mappings (v2) Andrey Vagin 2015-07-14 18:08 ` Oleg Nesterov 2015-07-14 18:08 ` Oleg Nesterov 2015-07-15 2:02 ` David Ahern 2015-07-15 2:02 ` David Ahern 2015-07-06 8:47 ` [PATCH 13/24] task_diag: shows memory consumption for " Andrey Vagin 2015-07-06 8:47 ` [PATCH 14/24] task_diag: add a marcos to enumirate memory mappings Andrey Vagin 2015-07-06 8:47 ` [PATCH 15/24] proc: give task_struct instead of pid into first_tid Andrey Vagin 2015-07-14 18:11 ` Oleg Nesterov 2015-07-06 8:47 ` [PATCH 16/24] proc: move first_tid and next_tid out of proc Andrey Vagin 2015-07-06 8:47 ` [PATCH 17/24] task_diag: add ability to dump theads Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 8:47 ` [PATCH 18/24] task_diag: add ability to handle one task in a continious mode Andrey Vagin 2015-07-06 8:47 ` [PATCH 19/24] task_diag: Add option to dump all threads for all tasks Andrey Vagin 2015-07-06 8:47 ` [PATCH 20/24] task_diag: Only add VMAs for thread_group leader Andrey Vagin 2015-07-14 17:47 ` Oleg Nesterov 2015-07-14 17:47 ` Oleg Nesterov 2015-07-15 2:01 ` David Ahern 2015-07-15 13:31 ` Oleg Nesterov 2015-07-15 13:31 ` Oleg Nesterov 2015-07-06 8:47 ` [PATCH 21/24] task diag: Add support for TGID attribute Andrey Vagin 2015-07-06 8:47 ` [PATCH 22/24] Documentation: add documentation for task_diag Andrey Vagin 2015-07-06 8:47 ` [PATCH 23/24] selftest: check the task_diag functinonality Andrey Vagin 2015-07-06 8:47 ` [PATCH 24/24] task_diag: Enhance fork tool to spawn threads Andrey Vagin 2015-07-06 8:47 ` Andrey Vagin 2015-07-06 17:10 ` [PATCH 0/24] kernel: add a netlink interface to get information about processes (v2) Andy Lutomirski 2015-07-07 15:43 ` Andrew Vagin 2015-07-07 15:56 ` Andy Lutomirski 2015-07-07 15:56 ` Andy Lutomirski 2015-07-07 16:17 ` David Ahern 2015-07-07 16:17 ` David Ahern 2015-07-07 16:24 ` Andy Lutomirski 2015-07-07 16:41 ` David Ahern 2015-07-07 16:41 ` David Ahern 2015-07-08 16:10 ` Andrew Vagin 2015-07-08 16:10 ` Andrew Vagin 2015-07-08 17:39 ` Andy Lutomirski 2015-07-08 22:49 ` Andrey Vagin 2015-07-08 23:48 ` Andy Lutomirski 2015-07-08 23:48 ` Andy Lutomirski 2015-07-07 16:25 ` Arnaldo Carvalho de Melo 2015-07-07 16:25 ` Arnaldo Carvalho de Melo 2015-07-07 16:27 ` Andy Lutomirski 2015-07-07 16:27 ` Andy Lutomirski 2015-07-07 16:56 ` David Ahern 2015-07-07 16:56 ` David Ahern 2015-11-24 15:18 ` Andrew Vagin 2015-11-24 15:18 ` Andrew Vagin 2015-12-03 23:20 ` Andy Lutomirski 2015-12-03 23:20 ` Andy Lutomirski 2015-12-03 23:43 ` Arnd Bergmann 2015-12-14 8:05 ` Andrew Vagin 2015-12-14 8:05 ` Andrew Vagin 2015-12-14 7:52 ` Andrew Vagin 2015-12-14 7:52 ` Andrew Vagin 2015-12-14 22:38 ` Andy Lutomirski 2015-12-15 15:53 ` Andrew Vagin 2015-12-15 15:53 ` Andrew Vagin 2015-12-15 16:43 ` Andy Lutomirski 2015-12-15 16:43 ` Andy Lutomirski
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