From: Andrew Morton <akpm@linux-foundation.org>
To: Nathan Zimmer <nzimmer@sgi.com>
Cc: mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de,
johnstul@us.ibm.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND 2/4] sched: /proc/sched_debug fails on very very large machines.
Date: Wed, 16 Jan 2013 13:56:47 -0800 [thread overview]
Message-ID: <20130116135647.019cbe8d.akpm@linux-foundation.org> (raw)
In-Reply-To: <1358286372-13777-3-git-send-email-nzimmer@sgi.com>
On Tue, 15 Jan 2013 15:46:10 -0600
Nathan Zimmer <nzimmer@sgi.com> wrote:
> On systems with 4096 cores attemping to read /proc/sched_debug fails.
> We are trying to push all the data into a single kmalloc buffer.
> The issue is on these very large machines all the data will not fit in 4mb.
>
> A better solution is to not us the single_open mechanism but to provide
> our own seq_operations and treat each cpu as an individual record.
>
> The output should be identical to previous version.
>
> ...
>
> + int cpu = (unsigned long)(v - 2);
Again, the meaning of the magic offsets are unobvious to readers of
this code.
> - SEQ_printf(m, "\n");
> + if (cpu != -1)
> + print_cpu(m, cpu);
Same concerns with cpu hotplug.
> + else
> + sched_debug_header(m);
>
> return 0;
> }
next prev parent reply other threads:[~2013-01-16 21:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-15 21:46 [PATCH RESEND 0/4] /proc/schedstat and /proc/sched_debug fail at 4096 Nathan Zimmer
2013-01-15 21:46 ` [PATCH RESEND 1/4] sched: /proc/sched_stat fails on very very large machines Nathan Zimmer
2013-01-16 21:53 ` Andrew Morton
2013-01-17 22:36 ` Nathan Zimmer
2013-01-15 21:46 ` [PATCH RESEND 2/4] sched: /proc/sched_debug " Nathan Zimmer
2013-01-16 21:56 ` Andrew Morton [this message]
2013-01-15 21:46 ` [PATCH RESEND 3/4] timer_list: split timer_list_show_tickdevices Nathan Zimmer
2013-01-16 22:09 ` Andrew Morton
2013-01-15 21:46 ` [PATCH RESEND 4/4] timer_list: Convert timer list to be a proper seq_file Nathan Zimmer
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