[[PATCH RT 0/6] Linux 3.14.48-rt49-rc1] On 06/08/2015 (Thu 18:17) Steven Rostedt wrote:
>
> Dear RT Folks,
>
> This is the RT stable review cycle of patch 3.14.48-rt49-rc1.
>
> Please scream at me if I messed something up. Please test the patches too.
>
> The -rc release will be uploaded to kernel.org and will be deleted when
> the final release is out. This is just a review release (or release candidate).
>
> The pre-releases will not be pushed to the git repository, only the
> final release is.
>
> If all goes well, this patch will be converted to the next main release
> on 8/10/2015.
>
> Note, these changes appear to make NO_HZ_FULL work as well as 3.18-rt does.
Appears to pass a simple sanity test here as well. Built basically a
defconfig + RT_FULL + NOHZ_FULL + FHANDLE + DEVTMPFS and ran this simple
test "t" -- meant to test 1st NOHZ and then NOHZ_FULL (loaded core).
Bootargs (below) and irqaffine and rcu-affine scripts (also below) are
meant to dump all housekeeping crap onto core zero.
---------------------------------------
root@testbox:/home/paul# cat t
cat /proc/interrupts |grep LOC
sleep 5
cat /proc/interrupts |grep LOC
taskset -c 5 ./eatme &
sleep 5
cat /proc/interrupts |grep LOC
kill %
root@testbox:/home/paul# ./t
LOC: 220787 1635 1614 1597 1579 1563 1543 1529 1512 1492 1414 1392 1375 1360 1342 1327 1307 1290 1277 1260 Local timer interrupts
LOC: 225795 1637 1616 1597 1579 1563 1543 1529 1512 1492 1414 1392 1375 1362 1345 1329 1310 1293 1279 1262 Local timer interrupts
LOC: 230800 1637 1616 1599 1582 1583 1545 1532 1514 1494 1416 1394 1377 1362 1345 1329 1310 1293 1279 1262 Local timer interrupts
root@testbox:/home/paul# jobs
root@testbox:/home/paul# cat /proc/version
Linux version 3.14.48-rt49-rc1-00071-g3fdc6bccf1b7 (paul@yow-dellw-pg2) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #1 SMP PREEMPT RT Sat Aug 8 15:08:25 EDT 2015
root@testbox:/home/paul# cat /proc/cmdline
root=/dev/sda2 ro console=ttyS0,115200 isolcpus=1-20 rcu_nocbs=1-20 rcu_nocb_poll nohz_full=1-20 irqaffinity=0 idle=poll tsc=perfect
root@testbox:/home/paul# cat no-rcu
for i in `pgrep rcuo` ; do taskset -c -p 0 $i ; done
root@testbox:/home/paul# cat clear-core
#!/bin/bash
# for all interrupting devices; move them to core zero; assumes that
for i in `cat /proc/interrupts | grep '^ *[0-9]*[0-9]:' |awk {'print $1}'|sed 's/:$//' `; do
# Timer
if [ "$i" = "0" ]; then
continue
fi
# cascade
if [ "$i" = "2" ]; then
continue
fi
echo setting $i to affine for core zero
echo 1 > /proc/irq/$i/smp_affinity
done
root@testbox:/home/paul#
---------------------------------------
So we took 20 IRQs in 5s, or 4/s ; not quite the 1/s minimum, but definitely not
the HZ/s we'd get w/o NOHZ_FULL. Re-running it got consistently 18-20 IRQ / 5s.
I specifically did NOT unplug and replug cores to "clean" them of tasks; the
hotplug code just seems to unstable for that from what I've seen in the past,
and by the looks of the irq counts above, there was no need to either.
The rootfs was basically a ubu 14.10 server install (no X11/gfx) -- not that
it should matter - so long as other tasks weren't running on the nohz cores.
Paul.
--
>
> Enjoy,
>
> -- Steve
>
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