On Fri, Jan 10, 2025 at 4:32 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > On Fri, Jan 10, 2025 at 11:32:46AM +0800, Jason Wang wrote: > > On Wed, Jan 8, 2025 at 7:35 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > > > On Mon, Nov 11, 2024 at 10:55:38AM +0800, Jason Wang wrote: > > > > There's no need to sync DMA for CPU on mapping errors. So this patch > > > > skips the CPU sync in the error handling path of DMA mapping. > > > > > > > > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> > > > > > > > > > So as I said, I do not get why we are optimizing error paths. > > > The commit log at least needs to be improved to document > > > the motivation. > > > > As replied before. Does the following make more sense? > > > > 1) dma_map_sg() did this > > 2) When the driver tries to submit more buffers than SWIOTLB allows, > > dma_map might fail, in these cases, bouncing is useless. > > > > Thanks > > About 2 - it's an error path. Is there a reason to think it's common? For example, doing FIO testing with 1M or larger requests when SWIOTLB is enabled. > About 1 - ok reasonable. You can say "while we have no data on how > common this is, it is consistent with what dma_map_sg does". Ok. Thanks > > -- > MST >
