Have a machine running the latest devel version nginx-0.7.33 (tried
with same results) for serving small (less than 10K images) and am
tcpdump that some SYN packets are not responded to right away.The
does retransmit these image requests every second and on the 2nd or 3rd
resent SYN, I finally start seeing and ACK, and the images load.
It is very indeterministic as to when it happens and can only reproduce
some of the time. When it does occur the outcome is a page with some
loaded and others (whose SYN packets are not ACKs) are not loaded…a
seconds later they load.
Typically the system has ~2000 active connections, most in keep alive.
load is around 100-200 req/sec.
I have tries all sorts of settings and configurations suggested in the
maillist but I still dont have the solution for this issue. from 1 to 4
workers, changing the connection counts, different even handlers, kernel
It just seems so anecdotal to just change a bunch of settings without
able to what is happening internally.
I’d like to be able to debug a little deeper to find out what is
to these packets.
How would I go about debugging what is the cause of it. Is it the
driver, kernel, or nginx? What kind of tools and debugging options can
model name : Intel® Xeon® CPU X3210 @ 2.13GHz
Linux n06 2.6.18-92.1.22.el5 #1 SMP Tue Dec 16 12:03:43 EST 2008 i686
Advertised auto-negotiation: Yes
Port: Twisted Pair
Supports Wake-on: g
Current message level: 0x000000ff (255)
Link detected: yes
firmware-version: 5721-v3.61, ASFIPMI v6.21
avg-cpu: %user %nice %system %iowait %steal %idle
0.10 0.00 0.20 2.43 0.00 97.27
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await
sda 0.00 0.00 27.40 0.00 443.20 0.00 16.18 0.10 3.50 3.32 9.10
no overruns or errors on interface.