Estoy buscando unos pocos usuarios de Linode 64 actualmente en hosts en el centro de datos de Fremont (host9 y superiores) para ayudar a probar un nuevo parche de rendimiento para el host y UML.
UML trabaja utilizando ptrace, una función de Linux para interceptar las llamadas al sistema realizadas por las aplicaciones. Cuando tu UML hace una llamada al sistema, el host intercepta la llamada, realiza el trabajo dentro de UML, y anula la llamada al sistema en el host convirtiendo esa llamada al sistema en "getpid" en el host. El problema con esto es que genera dos cambios de contexto en el host.
Con los [url=http://perso.wanadoo.fr/laurent.vivier/UML/
]sysemu patches[/url] en el host y en UML, no se molesta en ejecutar "getpid", reduciendo así el número de cambios de contexto de 2 a 1.
[b]Puntos de referencia[/b]
Aquí hay algunos benchmarks del "mundo real" usando el script run-all-tests de Mysql:
http://www.theshore.net/~caker/uml/sysemu-benchmarks.txt
En resumen, las pruebas se ejecutaron un [b]33% más rápido[/b] que sin los parches de sysemu.
[b]Detalles[/b]
Te migraremos al host25, manteniendo tu espacio en el host anterior reservado (en caso de que necesitemos migrarte de nuevo). En caso de que nunca hayas migrado antes, se trata de un proceso automatizado que mueve tus imágenes del sistema de archivos al nuevo host. No se requiere ningún cambio por tu parte, y el tiempo de inactividad se limita a lo que se tarde en copiar tus imágenes (normalmente menos de 15 minutos para 3GB).
Establezca su perfil de configuración para arrancar el kernel 2.4.26-linode29-1um
[*] Intenta romper las cosas[/lista]
Si las cosas van bien durante unos días, lo consideraré estable y abriré el servidor al público. Después de otras semanas, podemos mover los otros hosts a este kernel.
En segundo lugar, esto ayudará a probar 2.6.7-rc1 en el host, una actualización del actual kernel 2.6.4.
En tercer lugar, también me gustaría que algunos de ustedes probaran el kernel 2.4.26-linode29-1um, para asegurarse de que sigue funcionando correctamente en hosts sin los parches de sysemu. Por favor, háganme saber su experiencia con este kernel. En hosts no habilitados para sysemu, debería funcionar igual que los anteriores kernels de linode .
Hazme saber si estás interesado...
Gracias.
-Chris
Comentarios (17)
Three updates in one test? You’ve got ball-balls Chris!
😀
— James
I’m interested….let do it!
[quote:0999715663=”mcowger”]I’m interested….let do it![/quote]
Great. I haven’t patched a 2.6-um kernel with the sysemu patches yet, so for now go with the 2.4.26-linode29-1um kernel. I’ll update this thread when the 2.6 version is out.
Thanks!
-Chris
I’m game. What do I need to do?
Terry
[quote:31f75d1a84=”terryr”]I’m game. What do I need to do?[/quote]
Login, shutdown, and press the migrate button. After the migration, reboot.
BTW, 5 users have moved over to host25 and so far so good.
-Chris
Done! Are you looking for any specific feedback?
[quote:5c2da2598a=”terryr”]Done! Are you looking for any specific feedback?[/quote]
I pretty much know there’s a performance improvement already, but hearing about that would be nice. It might be kind of difficult to pin down, unless you run specific tests and compare them against the linode28 kernel. Secondly, I wanted to generate some load on the host kernel, and the linode29 kernel, just to make sure the stability is still there.
Thanks!
-Chris
I loaded a fresh Fedora Core 1 distro. Noticed immediately how much faster it is. Ran locate -u which was noticeably faster. Ran top and saw something strange. About every two seconds, there’s a cycle. See pics below. irq goes up to 0.9% and softirq goes up to 49.5% and iowait is 49.5%, then it all drops to 0 for 2 seconds and goes back up again for two seconds.
[img]http://futurecourse.com/files/no_softirq.gif[/img]
[img]http://futurecourse.com/files/softirq.gif[/img]
I don’t recall this happening when I looked at top on the old host. Or did I just miss it?
Terry
I am seeing stragne problems with mysql that I did not see before moving over. Whenever, I try to connect I get this message:
ERROR 2002: Can’t connect to local MySQL server through socket ‘/var/run/mysqld/mysqld.sock’ (2)
This is because mysqld either keeps hanging or completely crashes.
It will run fine for a few hours and then just die. I can’t explain why.
I will keep everyone posted.
John
[quote:04e5122a27=”jftuga”]I am seeing stragne problems with mysql that I did not see before moving over. Whenever, I try to connect I get this message:
ERROR 2002: Can’t connect to local MySQL server through socket ‘/var/run/mysqld/mysqld.sock’ (2)
This is because mysqld either keeps hanging or completely crashes.
It will run fine for a few hours and then just die. I can’t explain why.[/quote]
I’ve noticed your Linode using a lot of swap, so perhaps you’re running out of memory and the OOM (Out Of Memory) killer is kicking in…
-Chris
[quote:2ab259ee1d=”terryr”]I don’t recall this happening when I looked at top on the old host. Or did I just miss it? [/quote]
I’ll give this a shot, too, but.. would you mind rebooting into the linode28 kernel and seeing if you can reproduce this?
I somehow doubt the SYSEMU patch would be the cause of this, or the mysql problem…
-Chris
I have modified the mysql server for a small memory footprint using the my-small.cnf that comes with the src distro.
I will let you kno if this helps.
Also, I am using a lot of swap, and am considering upgrading to a 96 or 128 when they become available.
-John
[quote:befbb85d95=”caker”]I’ll give this a shot, too, but.. would you mind rebooting into the linode28 kernel and seeing if you can reproduce this? [/quote]
Did that yesterday with no change, but when I checked this morning, I’m at 0.1% for irq and softirq and it cycles with iowait at 0.2%. The high initial numbers didn’t seem to affect performance at all.
—
Terry
where is the migrate button? I shutodown and clicked around but I never found it.
[quote:f84ba42be4=”bakins”]where is the migrate button? I shutodown and clicked around but I never found it.[/quote]
This is something I have to set up for you first (which I just did). Login and you should see it.
Testing has gone very well. In fact, the machine is “live”, 2.6.7-rc1 is performing great (on the host), and the linode29 kernel works perfectly on SYSEMU and non-SYSEMU patched hosts.
I consider this test done, but go ahead and make the move — let me know what you think.
-Chris
I was out of town for a week.
I’ve now migrated and am testing. Everything seems to work. I’m testing out plone. I’ll do some tests and get back.
interesting… is this similar to the skas patch?