我正在寻找目前在弗里蒙特数据中心的主机上的几个Linode 64用户（host9及以上），以帮助测试主机和UML的新性能补丁。
UML 通过使用 ptrace 工作，这是 Linux 的一个功能，用于拦截应用程序的系统调用。 当你的 UML 进行系统调用时，主机会拦截该调用，在 UML 内部执行工作，并通过在主机上将该系统调用转换为 "getpid "来使主机上的系统调用无效。 这样做的问题是，它在主机上产生了两个上下文切换。
使用[url=http://perso.wanadoo.fr/laurent.vivier/UML/
]主机上的sysemu补丁[/url]和UML中的补丁，它不需要运行 "getpid"，从而将上下文切换的次数从2次减少到1次。
[b]基准[/b]
这里有一些使用Mysql的run-all-test脚本的 "真实世界 "基准：
http://www.theshore.net/~caker/uml/sysemu-benchmarks.txt
简而言之，测试比没有sysemu补丁时快了[b]33%[/b]。
[b]细节[/b]
[list][*] 我们将把你迁移到host25，保留你在前一个主机上的位置（以备我们需要把你迁移回来）。 如果你以前没有迁移过，这是一个自动的过程，将你的文件系统镜像转移到新的主机上。 你不需要做任何改变，停机时间仅限于复制你的图像所需的时间（通常3GB的图像少于15分钟左右）。
[*] 设置你的配置文件以启动2.4.26-linode29-1um内核。
[*] 尝试破坏东西[/list]
如果几天内事情进展顺利，我就认为它已经稳定，并向公众开放服务器。 再过几个星期，我们就可以把其他主机移到这个内核上。
其次，这将有助于在主机上测试2.6.7-rc1，这是目前2.6.4内核的升级。
第三，我还想让你们中的一些人测试一下2.4.26-linode29-1um内核，以确保它在没有sysemu补丁的主机上仍能正常工作。 请让我知道你使用这个内核的经验。 在没有启用sysemu的主机上，它的性能应该和以前的linode内核一样。
如果你有兴趣，请告诉我...
谢谢!
-冯小刚
评论 (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?