Timeouts gone wild on ia64
Subsystems (3)
PATCH 1/1 Timeouts gone wild on ia64
Here is a patch that greatly reduces that number of timeout (and EIO errors with soft mounts) that occur when a fast client is talking to a slow server.
We were noticing a large number of EIO errors when a ia64 client was talking to a x86 server with soft mounts (ala autofs)....
True, EIO errors should be expect with soft mounts but it turns out that thousands of timeouts were occurring on a ia64 client compared to 50 to 60 timeouts with a x86 client when talking to the same slow server and generating the same traffic.
What this patch does is make the minimal Round Trip time value relative to HZ. So When HZ is greater (as in the case of ia64) the minimal value goes up.
Comments?
SteveD.
net/sunrpc/timer.c renamed from net/sunrpc/timer.c.orig +1 -1
@@ -8,7 +8,7 @@#define RPC_RTO_MAX (60*HZ)#define RPC_RTO_INIT (HZ/5) -#define RPC_RTO_MIN (2) +#define RPC_RTO_MIN (HZ/30)void rpc_init_rtt (struct rpc_rtt *rt,long timeo)
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" " == Steve Dickson <[email protected]> writes:
> What this patch does is make the minimal Round Trip time value > relative to HZ. So When HZ is greater (as in the case of ia64) > the minimal value goes up.
> Comments?
1/30 of a second is a long time. Why that particular choice?
Note: "It works" won't cut ice as that is completely a function of the choice of hardware.
Cheers,
Trond
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Enterprise Linux Forum Conference & Expo, June 4-6, 2003, Santa Clara The only event dedicated to issues related to Linux enterprise solutions www.enterpriselinuxforum.com
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Hi Trond,
Quoted 9 lines · Trond Myklebust
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" " == Steve Dickson <[email protected]> writes:
What this patch does is make the minimal Round Trip time value relative to HZ. So When HZ is greater (as in the case of ia64) the minimal value goes up.
Comments?
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1/30 of a second is a long time. Why that particular choice?
Note: "It works" won't cut ice as that is completely a function of the choice of hardware.
I realize this but... I figured waiting a few extra ticks of time before timing out was probably a good thing with respect to soft mounts to slow servers... Especially since EIO errors can be pretty disruptive...
And as I see, its a no-op with a fast (or slow) client talking to a fast server because the timeout will should never happen... (i.e. the waiting thread will get the response before the time out occurs)....
SteveD.
-------------------------------------------------------
Enterprise Linux Forum Conference & Expo, June 4-6, 2003, Santa Clara The only event dedicated to issues related to Linux enterprise solutions www.enterpriselinuxforum.com
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