On Fri, 2013-06-28 at 14:58 +0200, Bart Van Assche wrote: > From: Vu Pham <[email protected]> > > Allow the InfiniBand RC retry count to be configured by the user > as an option in the target login string. The transport layer > timeout in nanoseconds is computed as follows from the retry count: > > rc_timeout = rc_retry_count * 4 * 4096 * (1 << qp->timeout) > > The default value for tl_retry_count is changed from 7 into 2. > Hence with a qp->timedout value of 19 this patch reduces the > default transport layer timeout from about 60s to about 17s. The > purpose of this patch is to reduce the time needed for SCSI error > handling significantly and at the same time to avoid activating > the SCSI error handler on an IB path with a regular BER or due to > brief IB network congestion.
I keep vacillating between preserving the default of 7 and opting for easier/optimized configuration for the common case. It my internal argument over this today, I wondered about changing the QP timeout instead -- doesn't that achieve your goals of allowing for errors and network congestion while optimizing for a reasonable fabric? Going from 19 to 17 drops the timeout by about the same amount, while allowing for more errors. I agree that one or both of the items should be configurable, but I'm still worried about changing the defaults, given the feed back from those that want to use IB over the WAN. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
