Xuan Zhuo
2023-Aug-15 09:27 UTC
[PATCH vhost v13 05/12] virtio_ring: introduce virtqueue_dma_dev()
On Tue, 15 Aug 2023 15:50:23 +0800, Jason Wang <jasowang at redhat.com> wrote:> On Tue, Aug 15, 2023 at 2:32?PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > > > Hi, Jason > > > > Could you skip this patch? > > I'm fine with either merging or dropping this. > > > > > Let we review other patches firstly? > > I will be on vacation soon, and won't have time to do this until next week.Have a happly vacation.> > But I spot two possible "issues": > > 1) the DMA metadata were stored in the headroom of the page, this > breaks frags coalescing, we need to benchmark it's impactNot every page, just the first page of the COMP pages. So I think there is no impact.> 2) pre mapped DMA addresses were not reused in the case of XDP_TX/XDP_REDIRECTBecause that the tx is not the premapped mode. Thanks.> > I see Michael has merge this series so I'm fine to let it go first. > > Thanks > > > > > Thanks. > > >
Jason Wang
2023-Aug-16 01:13 UTC
[PATCH vhost v13 05/12] virtio_ring: introduce virtqueue_dma_dev()
On Tue, Aug 15, 2023 at 5:40?PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote:> > On Tue, 15 Aug 2023 15:50:23 +0800, Jason Wang <jasowang at redhat.com> wrote: > > On Tue, Aug 15, 2023 at 2:32?PM Xuan Zhuo <xuanzhuo at linux.alibaba.com> wrote: > > > > > > > > > Hi, Jason > > > > > > Could you skip this patch? > > > > I'm fine with either merging or dropping this. > > > > > > > > Let we review other patches firstly? > > > > I will be on vacation soon, and won't have time to do this until next week. > > Have a happly vacation. > > > > > But I spot two possible "issues": > > > > 1) the DMA metadata were stored in the headroom of the page, this > > breaks frags coalescing, we need to benchmark it's impact > > Not every page, just the first page of the COMP pages. > > So I think there is no impact.Nope, see this: if (SKB_FRAG_PAGE_ORDER && !static_branch_unlikely(&net_high_order_alloc_disable_key)) { /* Avoid direct reclaim but allow kswapd to wake */ pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) | __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY, SKB_FRAG_PAGE_ORDER); if (likely(pfrag->page)) { pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER; return true; } } The comp page might be disabled due to the SKB_FRAG_PAGE_ORDER and net_high_order_alloc_disable_key.> > > > 2) pre mapped DMA addresses were not reused in the case of XDP_TX/XDP_REDIRECT > > Because that the tx is not the premapped mode.Yes, we can optimize this on top. Thanks> > Thanks. > > > > > I see Michael has merge this series so I'm fine to let it go first. > > > > Thanks > > > > > > > > Thanks. > > > > > >