On 01/19/2016 11:24 PM, Igor Mammedov wrote: > On Mon, 18 Jan 2016 10:42:29 +0800 > Jason Wang <jasowang@xxxxxxxxxx> wrote: > >> > Current pre-sorted memory region array has some limitations for future >> > device IOTLB conversion: >> > >> > 1) need extra work for adding and removing a single region, and it's >> > expected to be slow because of sorting or memory re-allocation. >> > 2) need extra work of removing a large range which may intersect >> > several regions with different size. >> > 3) need trick for a replacement policy like LRU >> > >> > To overcome the above shortcomings, this patch convert it to interval >> > tree which can easily address the above issue with almost no extra >> > work. >> > >> > The patch could be used for: >> > >> > - Extend the current API and only let the userspace to send diffs of >> > memory table. >> > - Simplify Device IOTLB implementation. > I'm curios how performance changes on translate_desc() hot-path in > default case and in the case of 256 memory regions? > Haven't measured this. But consider both methods are O(logN), should be no noticeable difference. Will measure it in the future. The main user is for the device IOTLB API[1], which: - have thousands of userspace memory region sections - may dynamically adding or removing one or some of the regions - need a replacement algorithm like LRU [1] https://lkml.org/lkml/2015/12/31/16 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
