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Groups > linux.kernel > #1178705
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|---|---|
| From | Andy Lutomirski <luto@amacapital.net> |
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 0/24] kernel: add a netlink interface to get information about processes (v2) |
| Date | Tue, 07 Jul 2015 18:30:02 +0200 |
| Message-ID | <pJDUS-7UN-5@gated-at.bofh.it> (permalink) |
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| X-Original-To | David Ahern <dsahern@gmail.com> |
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| X-Original-Cc | Andrew Vagin <avagin@odin.com>, Andrey Vagin <avagin@openvz.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Linux API <linux-api@vger.kernel.org>, Oleg Nesterov <oleg@redhat.com>, 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>, Pavel Odintsov <pavel.odintsov@gmail.com> |
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| Xref | aioe.org linux.kernel:1178705 |
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On Tue, Jul 7, 2015 at 9:17 AM, David Ahern <dsahern@gmail.com> wrote: > On 7/7/15 9:56 AM, Andy Lutomirski wrote: >> >> Netlink is fine for these use cases (if they were related to the >> netns, not the pid ns or user ns), and it works. It's still tedious >> -- I bet that if you used a syscall, the user code would be >> considerable shorter, though. :) >> >> How would this be a problem if you used plain syscalls? The user >> would make a request, and the syscall would tell the user that their >> result buffer was too small if it was, in fact, too small. > > > It will be impossible to tell a user what sized buffer is needed. The size > is largely a function of the number of tasks and number of maps per thread > group and both of those will be changing. With the growing size of systems > (I was sparc systems with 1024 cpus) the workload can be 10's of thousands > of tasks each with a lot of maps (e.g., java workloads). That amounts to a > non-trivial amount of data that has to be pushed to userspace. > > One of the benefits of the netlink approach is breaking the data across > multiple messages and picking up where you left off. That infrastructure is > already in place. > How does picking up where you left off work? I assumed the interface was something along the lines of "give me information starting from pid N", but maybe I missed something. --Andy -- 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/
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Re: [PATCH 0/24] kernel: add a netlink interface to get information about processes (v2) David Ahern <dsahern@gmail.com> - 2015-07-07 18:20 +0200
Re: [PATCH 0/24] kernel: add a netlink interface to get information about processes (v2) Andy Lutomirski <luto@amacapital.net> - 2015-07-07 18:30 +0200
Re: [PATCH 0/24] kernel: add a netlink interface to get information about processes (v2) David Ahern <dsahern@gmail.com> - 2015-07-07 18:50 +0200
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