On Tue, May 26, 2009 at 09:47:02AM -0500, James Bottomley wrote: > > Yeah, we can inline the sense buffer but as we discussed in the past > > several times, there are some good reasons that we should not do so, I > > think. > > There are several other approaches: > > 1. Keep the sense buffer packed in the command but disallow DMA to > it, which fixes all the alignment problems. Then we supply a > set of rotating DMA buffers to drivers which need to do the DMA > (which isn't the majority). > 2. Sense is a comparative rarity, so us a more compact pooling > scheme and discard sense for reuse as soon as we know it's not > used (as in at softirq time when there's no sense collected). > > I'd need a little more clarity on the actual size of the problem before > making any choices. I'm not sure if this is what you meant by option 2 or not, but one proposal was to keep a number of sense buffers around per-host, and only allocate extras when we run close to empty. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
