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, Jason
