Messages in this thread | | | Date | Fri, 22 Aug 2003 00:41:39 -0400 | From | Yaoping Ruan <> | Subject | kernel hangs up running web server |
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Hi,
I posted this kernel lock problem sometime last week. Though there're helpful suggestion, I haven't found any useful information from the kernel. I've tried 2.6.0-test3 and the same thing happened. The machine couldn't be reached by "ping" after hanging up. But the bug may not be in sendfile() or epoll() since a version without these two system call also causes kernel lock.
Thus I've made both the server (Flash) and the workload generator (Flexiclient) available at: www.cs.princeton.edu/~yruan/flash and would appreciate if any of the developers could try them out. To run the test
1. generate fileset at server side by copying over fileset and ./fileset -s zipfset -n #DIRS 2. compile Flash (may change options in config.h) and run ./flash -user YOUR_ACCOUNT 3. run client as: ./zipfgen -s spec -n #DIRS | ./batcher 5 | ./flexiclient -host HOST -time SECONDS -active 1000 (it's a rarely happened bug, better to run more than 1800 seconds, with 1000 connections)
Thanks a lot
- Yaoping
Andrew Morton wrote:
> Yaoping Ruan <yruan@cs.princeton.edu> wrote: > > > > Hi, > > > > Recently we updated a user space web server to use the sendfile() and > > epoll() interface, and tried to measure the performance with SpecWeb99 > > benchmark. As the load increases, e.g a SpecWeb99's target score of 600 > > connection, the kernel sometimes hangs up without any logging > > information, and the only way left is to push the reset button to > > reboot. > > > > We also made similar updates to use sendfile() and kevent() on FreeBSD > > and achieved a score of 1000 connections. Thus the possibility of > > application bug is low (also it is a user space server). Before the > > sendfile() and epoll() change, it was also fine but only could get a > > SpecWeb99 score of 500. > > > > The kernel we were using was 2.4.21 with the epoll patch applied. Since > > the epoll man pages mention the interface is stabilized in 2.5.66, we > > also tried 2.5.66 but didn't see anything better. The machine is a PIII > > Xeon processor-based Intel server motherboard, with 2 CPU support but > > only 1 is used, Maxtor Diamond IDE disk, Promise Ultra DMA 66 > > controller, and a single Netgear GA621 gigabit ethernet network adapter. > > > > Definitely a kernel bug. > > Could you please test 2.6.0-test3? If that has the same problem then > some initial steps would be: > > - Boot the kernel with the "nmi_watchdog=1" option on the kernel boot > command line. (It needs to be an SMP-compiled kernel for this to work. > Or one which has the local APIC enabled in config) > > - Make sure that /proc/sys/kernel/sysrq was set to `1' after booting. > > - Can you still ping the machine after it hangs up? > > - Type ALT-SYSRQ-T and/pr ALT-SYSRQ-P on the keyboard, see if you get a trace. > > - ALT-SYSRQ-M may be interesting too (memory stats) > > If the nmi watchdog doesn't generate a trace then the sysrq keys should do > so. > > If the above does not provide us with enough information to solve the bug > then the next step would be for you to provide sufficient material for a > kernel developer to reproduce the problem. > > Thanks.
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