Re: Problem: Out of memory after 2days with 2GB RAM

From: Johannes Berg
Date: Thu Jun 12 2008 - 13:40:20 EST



> > Yeah, but why bother if we can just allocate 10% of the size, waste a
> > lot less memory etc. mac80211 isn't going to pass in a scatter/gather
> > frame anyway.
>
> Hope never dies. I actually have seen this speed up the throughput so
> I will dig into it anyway.

Well, you can always add it back later if you make the networking stack
and mac80211 support it. It's a two-line patch after all.

> > The more interesting thing is the pci_alloc_consistent allocation right
> > below that is also _huge_, but that's because of the stupid hardware
> > design, or can the hardware cope with having the descriptors non-linear
> > in memory?
>
> We talk after your next HW design. How will configure 265 * 16
> descriptors separately.

Well, considering that other hardware does manage to do things
differently (say Broadcom because I know their DMA engine), I don't know
why your hw designers went wild with this. All you need is an
"end-of-frame" flag. But that's not really interesting to discuss,
unless this is actually controlled by the microcode and you can change
it.

johannes

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