On Thu, Nov 17, 2011 at 5:04 AM, Łukasz Mierzwa <l.mier...@gmail.com> wrote:
> Dnia czwartek, 17 listopada 2011 11:40:55 Roberto De Ioris pisze:
>> Hi everyone, the support for Linux KSM has been added in current mercurial
>> tip
>>
>> http://projects.unbit.it/uwsgi/wiki/KSM
>>
>> If you host a good amount of uWSGi instances/processes on a recent
>> (>=2.6.32) linux kernel, try it.
>
> This is great feature that all who need to run multiple ruby apps will be
> thankful for, but I guess that one should add few zeros at the end of max-
> requests value and maybe disable idle option.
> The great thing about KSM is that it requires cpu power only to scan/merge
> pages, so when under high load one can disable KSM (echo 1 > ksm/run) and all
> the saving are still going to be there.
i dont think it's too expensive for KSM to merge pages later on if as
they die, so long as your aren't killing stuff off very quickly.
slightly OT, but this irritated me for hours -- apparently sysctl only
works with /proc/sys? and not /sys?? @#$@#??? no way to apply
settings at boot (debian has custom /etc/sysfs.conf, though). systemd
(what i use for init) only applies sysctl variables, not sysfs ...
so i wrote this:
# awk -vs=/sys/ -ve=
"!/^\s*(#|$)/{match($0,/^([^=]+)=(.*)$/,a);t(a);print a[2] > s
a[1];}function t(a, i){for(i=1;i<3;i++){gsub(/^\s*|\s*$/,e,a[i]);}}"
/etc/sysfs.conf
... and as a .service file (modeled from sysctl.service)
-----------------------------------------------------
[Unit]
Description=Apply Sysfs Variables
DefaultDependencies=no
Conflicts=shutdown.target
After=systemd-readahead-collect.service systemd-readahead-replay.service
Before=sysinit.target shutdown.target
ConditionPathExists=|/etc/sysfs.conf
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/bin/awk -vs=/sys/ -ve=
"!/^\s*(#|$)/{match($0,/^([^=]+)=(.*)$/,a);t(a);print a[2] > s
a[1];}function t(a, i){for(i=1;i<3;i++){gsub(/^\s*|\s*$/,e,a[i]);}}"
/etc/sysfs.conf
-----------------------------------------------------
... might be useful to some:
-----------------------------------------------------
# cat /etc/sysfs.conf
# Set KSM config at boot
kernel/mm/ksm/sleep_millisecs = 100
kernel/mm/ksm/run = 1
-----------------------------------------------------
... btw, as an example of KSMs power:
-----------------------------------------------------
# for x in /sys/kernel/mm/ksm/*; do printf "%s\t%s\n" "$(basename
"$x")" "$(<"$x")"; done | column -t; echo; free -m
full_scans 173
pages_shared 10039
pages_sharing 34206
pages_to_scan 100
pages_unshared 107191
pages_volatile 2578
run 1
sleep_millisecs 100
total used free shared buffers cached
Mem: 3958 1072 2886 0 30 293
-/+ buffers/cache: 748 3210
Swap: 2047 0 2047
-----------------------------------------------------
... this machine runs 4 KVM VMs at 256M each (ie. MORE than 1GB
dedicated), and guest + host RAM usage is less than 800MB ... savings
will be even more once i convert to 9p2000.L rootfs in all VMs, but
that's way OT for this list.
also see: http://code.google.com/p/uksm/
--
C Anthony
_______________________________________________
uWSGI mailing list
uWSGI@lists.unbit.it
http://lists.unbit.it/cgi-bin/mailman/listinfo/uwsgi
