Messages in this thread | | | Date | Mon, 3 Nov 2008 05:46:39 -0600 | From | Robin Holt <> | Subject | Re: [PATCH V2 0/2] enable irqs when waiting for rwlocks |
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On Fri, Oct 31, 2008 at 01:22:56PM -0700, Luck, Tony wrote: > > Any comments on my second patch series? Not even an Acked-by? Dislike of > > the concept? Should I post it again? > > Better response to interrupts is good, but it comes at the > cost of longer latency acquiring the lock (in the case where > an interrupt happens while we are waiting for the lock, and > the lock is freed while we are off executing the interrupt > handler). > > Any suggestions on how to measure the trade-off here? Possibly > it doesn't matter because this may only be significant when > the lock is heavily contended and you are probably aleady > hosed in this case.
Just a few years of experiencal evidence. The equivalent of this patch has been in the SuSE SLES10 kernel for years and not been detected as being negative.
Sorry I don't have more detail. The person at SGI who first detected this problem has long since left, and actually passed away from an aneurysm a couple years ago. The first version of the patch was in our one-off kernel based on Redhat's 2.4 kernel. The patch was not pushed to SuSE and the community for SLES9. It was in SLES10, but I can not find our internal tracking tool's record of it (searching is failing me this morning). Without that, I have not been able to find why it was not pushed to the community.
Thanks, Robin
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