On Tue, Sep 17, 2013 at 11:34:21AM -0400, Peter Hurley wrote:
> On 09/12/2013 09:09 PM, Fengguang Wu wrote:
> >On Fri, Sep 13, 2013 at 08:51:33AM +0800, Fengguang Wu wrote:
> >>Hi Peter,
> >>
> >>FYI, we noticed much increased vmap_area_lock contentions since this
> >>commit:
> >>
> >>commit 20bafb3d23d108bc0a896eb8b7c1501f4f649b77
> >>Author: Peter Hurley <pe...@hurleysoftware.com>
> >>Date: Sat Jun 15 10:21:19 2013 -0400
> >>
> >> n_tty: Move buffers into n_tty_data
> >>
> >> Reduce pointer reloading and improve locality-of-reference;
> >> allocate read_buf and echo_buf within struct n_tty_data.
> >
> >Here are some comparison between this commit [o] with its parent commit [*].
>
> Hi Fenguang,
>
> Can you give the particulars of the aim7 test runs below?
> I ask because I get _no_ added contention on the vmap_area_lock when I run
> these tests on a dual-socket xeon.
>
> What is the machine configuration(s)?
> Are you using the aim7 'multitask' test driver or your own custom driver?
> What is the load configuration (ie., constant, linearly increasing,
> convergence)?
> How many loads are you simulating?
The aim7 tests are basically
(
echo $HOSTNAME
echo $workfile
echo 1
echo 2000
echo 2
echo 2000
echo 1
) | ./multitask -t
> lock_stat.vmap_area_lock.holdtime-total
> [...]
> > 489739.50 +978.5% 5281916.05
> > lkp-ne04/micro/aim7/shell_rtns_1
> > 1601675.63 +906.7% 16123642.52
> > lkp-snb01/micro/aim7/exec_test
> [...]
> > 822461.02 +1585.0% 13858430.62
> > nhm-white/micro/aim7/exec_test
> > 9858.11 +2715.9% 277595.41
> > nhm-white/micro/aim7/fork_test
> [...]
> > 300.14 +2621.5% 8168.53
> > nhm-white/micro/aim7/misc_rtns_1
> > 345479.21 +1624.5% 5957828.25
> > nhm-white/micro/aim7/shell_rtns_1
>
>
> None of the tests below execute a code path that leads to get_vmalloc_info().
> The only in-kernel user of get_vmalloc_info() is a sysfs read of
> /proc/meminfo,
> which none of the tests below perform.
>
> What is reading /proc/meminfo?
Good point! That may explain it: I'm running a
loop:
cat /proc/meminfo
sleep 1
in all the tests.
Thanks,
Fengguang
> > lock_stat.vmap_area_lock.contentions.get_vmalloc_info
> >
> > 8cb06c983822103da1cf 20bafb3d23d108bc0a89
> >------------------------ ------------------------
> > 4952.40 +447.0% 27090.40
> > lkp-ne04/micro/aim7/shell_rtns_1
> > 28410.80 +556.2% 186423.00
> > lkp-snb01/micro/aim7/exec_test
> > 8142.00 +615.4% 58247.33
> > nhm-white/micro/aim7/exec_test
> > 1386.00 +762.6% 11955.20
> > nhm-white/micro/aim7/shell_rtns_1
> > 42891.20 +561.5% 283715.93 TOTAL
> > lock_stat.vmap_area_lock.contentions.get_vmalloc_info
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