On Tue, Dec 18, 2018 at 03:27:30PM -0700, Jason Gunthorpe wrote: > On Tue, Dec 11, 2018 at 01:37:50PM +0200, Leon Romanovsky wrote: > > From: Leon Romanovsky <leonro@xxxxxxxxxxxx> > > > > Changelog v0->v1: > > * Fixed commit message in patch 2 > > * Removed redundant brackets > > * Add FIXME comment > > * Flush workqueue to ensure no work is executed during ib_device dereg > > * Change declaration of sg_list ot be flex array > > * Fix rebase error > > > > Hi, > > > > In this series from Moni, we are implementing the new advise_mr() > > verb, which was proposed as RFC [1]. > > > > The verb advise_mr() borrows its definition from the system call > > madvise() by giving an advice to the driver about an address range > > that belongs to a memory region (MR), in opposite to madvise() which > > operates on addresses and has different logical semantics not suitable > > for MRs. > > > > This verb is used by applications to tell the kernel about expected > > memory usage to efficiently prepare it in advance, prior any following > > usage. Like with madvise(), the advise_mr verb does not interfere > > the semantics of the application, but can improve application performance. > > > > Being an advice, the kernel is free to ignore advise_mr() calls. > > > > Important example of such performance improvement hint is partial > > pre-fetching of an ODP MRs. > > > > Such pre-fetched ODP address ensure that range is exist before the actual > > IO is conducted. This would provide a way to reduce latency by overlapping > > paging-in and either compute time or IO to other ranges. > > > > Thanks > > > > [1] https://www.spinics.net/lists/linux-rdma/msg70592.html > > > > This series has merge conflict with commit: 4d5422a309de > > ("IB/mlx5: Skip non-ODP MR when handling a page fault") in rdma-rc. > > > > The resolution is as follow: > > 1. It is an error to ask "prefetch" for non-ODP MRs, because it came from explicit request. > > 2. It is OK to have non-ODP MRs in page-faults. > > > > + if (prefetch && !mr->umem->is_odp) { > > + ret = -EINVAL; > > + goto srcu_unlock; > > + } > > + > > + if (!mr->umem->is_odp) { > > + mlx5_ib_dbg(dev, "skipping non ODP MR (lkey=0x%06x) in page fault handler.\n", > > + key); > > + if (bytes_mapped) > > + *bytes_mapped += bcnt; > > + ret = 0; > > + goto srcu_unlock; > > + } > > > > Moni Shoua (3): > > IB/uverbs: Add helper to get array size from ptr attribute > > IB/uverbs: Add support to advise_mr > > IB/mlx5: Add advise_mr() support > > Applied to for next. I had to rebase it over the ops patches, which > wasn't hard, but please check my work. Thanks, It looks good. > > Thanks, > Jason
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