Still bug-hunting
Subsystems (2)
Hello.
I have found out that the slow-down issue with many sockets is a memory problem now. Not that I do not have enough but the vm isnt able to reclaim fast-enough. Problem temporarily solved by setting lower_zone_protection to 1024. Still I wonder why /proc/net/sockstat shows this:
sockets: used 1637
TCP: inuse 1761 orphan 179 tw 3743 alloc 1761 mem 54224
The send-buffer is set to 128 and the rcv-buffer to 16 so theoretically it should be 1637*144=235728 so I assume the buffers are allocated dynamically when they are really needed... I suppose the slow-down wouldnt appear if the buffers are allocated statically. Is there any way to check this?
Chris
David S. Miller
maintainerQuoted 1 line · On Sat, 05 Mar 2005 18:57:00 +0100 Christian Schmid <[email protected]>…
I have found out that the slow-down issue with many sockets is a memory problem now.
Thanks for the test case we asked for.
A message that is not in the archive (sent off-list or not yet received): [email protected]
A message that is not in the archive (sent off-list or not yet received): [email protected]
You as an expert should know that this is no one-liner. It is a very complex server with multiplexing and forking like Apache. I dont feel like writing an apache-like program just for testing. I hope you understand that I prefered investing my time in acutally searching the bug and now its found. Now I hope that you can fix it or at least tell me your ideas.
Quoted 13 lines · David S. Miller
Quoted 1 line · On Sat, 05 Mar 2005 19:36:05 +0100 Christian Schmid <[email protected]>…
Sorry? What do you mean?
I'm being sarcastic in that you didn't provide the test case we asked you to provide so we could reproduce the many-socket slowdown too and help you figure out what was going wrong.
David S. Miller
maintainerQuoted 4 lines · On Sat, 05 Mar 2005 19:54:49 +0100 Christian Schmid <[email protected]>…
You as an expert should know that this is no one-liner. It is a very complex server with multiplexing and forking like Apache. I dont feel like writing an apache-like program just for testing. I hope you understand that I prefered investing my time in acutally searching the bug and now its found. Now I hope that you can fix it or at least tell me your ideas.
You could give us the program you actually used, no writing necessary. Obviously you had this program, else you wouldn't have anything to report at all.
There's nothing "to write", you have it already by implication.
Instead, you told us "do something like this, or that" and lots of vague statements and brief incomplete code snippets, then expect us to figure out how the magic beans work and fix your problem.
And you want respect and help from us? :-)
Actually we are a company and the big ones decided to buy new servers to work-around this bug. This is a common technique in companies. I say this sucks and thats why I experienced in our production system in order to give linux something back by reporting and helping to fix a bug which only appears on big systems. I do not understand why you start flaming at me.
Quoted 21 lines · David S. Miller
Quoted 1 line · On Sat, 05 Mar 2005 19:54:49 +0100 Christian Schmid <[email protected]>…
You as an expert should know that this is no one-liner. It is a very complex server with multiplexing and forking like Apache. I dont feel like writing an apache-like program just for testing. I hope you understand that I prefered investing my time in acutally searching the bug and now its found. Now I hope that you can fix it or at least tell me your ideas.
You could give us the program you actually used, no writing necessary. Obviously you had this program, else you wouldn't have anything to report at all.
There's nothing "to write", you have it already by implication.
Instead, you told us "do something like this, or that" and lots of vague statements and brief incomplete code snippets, then expect us to figure out how the magic beans work and fix your problem.
And you want respect and help from us? :-)
* Christian Schmid <[email protected]> 2005-03-05 20:07
Quoted 5 lines
Actually we are a company and the big ones decided to buy new servers to work-around this bug. This is a common technique in companies. I say this sucks and thats why I experienced in our production system in order to give linux something back by reporting and helping to fix a bug which only appears on big systems. I do not understand why you start flaming at me.
It's quite simple, provide a test case and someone will start looking into the problem (given there is one). The information you provided so far is quite vague, it would be pure luck to spot the bug. You have do understand that looking into such a bug may cost dozens of hours or days if it can't be reproduced by the person. Nobody does this without at least very strong evidences that the bug actually exists and your appereance so far didn't help too much I guess.
Quoted 5 lines · Thomas Graf
* Christian Schmid <[email protected]> 2005-03-05 20:07
Quoted 1 line
Actually we are a company and the big ones decided to buy new servers to work-around this bug. This is a common technique in companies. I say this sucks and thats why I experienced in our production system in order to give linux something back by reporting and helping to fix a bug which only appears on big systems. I do not understand why you start flaming at me.
Quoted 7 lines
It's quite simple, provide a test case and someone will start looking into the problem (given there is one). The information you provided so far is quite vague, it would be pure luck to spot the bug. You have do understand that looking into such a bug may cost dozens of hours or days if it can't be reproduced by the person. Nobody does this without at least very strong evidences that the bug actually exists and your appereance so far didn't help too much I guess.
I just asked for a way how to change the dynamic memory-allocation for buffers to a static one. I dont think that this is much work and is a quite direct task.
Christian Schmid <[email protected]> :
[...]
Quoted 3 lines
I just asked for a way how to change the dynamic memory-allocation for buffers to a static one. I dont think that this is much work and is a quite direct task.
Simple answer: rewrite alloc_skb and friends.
--
Ueimor
In less-rude words: "No, this is not easy. No way, sorry."
Thank you for this information. I have sent very detailed bug-reports to LKML. Maybe you have read already.
Quoted 12 lines · Francois Romieu
Christian Schmid <[email protected]> :
[...]Quoted 1 line
I just asked for a way how to change the dynamic memory-allocation for buffers to a static one. I dont think that this is much work and is a quite direct task.
Simple answer: rewrite
alloc_skband friends.--
Ueimor
Christian Schmid <[email protected]> :
Quoted 1 line
In less-rude words: "No, this is not easy. No way, sorry."
If you can not distinguish a factual answer from a flame, it is time to take a break.
[...]
Quoted 2 lines
Thank you for this information. I have sent very detailed bug-reports to LKML. Maybe you have read already.
Just done so but I fail to see if you provided N. Piggin with the data he requested. Anyway, I can return to more basic issues since he and the others will do a better job than me.
--
Ueimor