Messages in this thread |  | | Subject | Re: [PATCH] starfire reads irq before pci_enable_device. | From | Jes Sorensen <> | Date | 12 Feb 2001 19:54:25 +0100 |
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>>>>> "Donald" == Donald Becker <becker@scyld.com> writes:
Donald> On 9 Feb 2001, Jes Sorensen wrote: >> The ia64 kernel has gotten mis aligned load support, but it's slow >> as a dog so we really want to copy the packet every time anyway >> when the header is not aligned. If people send out 802.3 headers or >> other crap on Ethernet then it's just too bad.
Donald> Note the word "required", meaning "must be done" Donald> vs. "recommended" meaning "should be done".
Donald> The initial issue was a comment in a starfire patch that Donald> claimed an IA64 bug had been fixed. The copy breakpoint Donald> change might have improved performance by doing a copy-align, Donald> but it didn't fix a bug.
I agree it was a bug, and yes it has been fixed.
Donald> That performance tradeoff was already anticipated: the Donald> 'rx_copybreak' value that was changed was a module parameter, Donald> not a constant. That allows a module-load-time tradeoff, Donald> based the specific implementation, of copying the received Donald> packet or accepting a few unaligned loads of the usually small Donald> IP header. See the comments in starfire.c, as well as several Donald> other bus-master drivers.
In this case it just results in a performance degradation for 99% of the usage. What about making the change so it is optimized away unless IPX is enabled?
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