search for: sg

DMA-related logic is separated from the virtqueue_add_split() to one new function. DMA address will be saved as sg->dma_address if use_dma_api is true, then virtqueue_add_split() will use it directly. Unmap operation will be simpler. The purpose of this is to facilitate subsequent support to receive dma address mapped by drivers. Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> --- drivers/v...

DMA-related logic is separated from the virtqueue_add_vring_split() to prepare for subsequent support for premapped. DMA address will be saved as sg->dma_address, then virtqueue_add_vring_split() will use it directly. If it is a premapped scene, the transmitted sgs should have saved DMA address in dma_address, and in virtio core, we need to pass virtqueue_map_sgs(). Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> --- driver...

This patch put the dma addr error check in vring_map_one_sg(). The benefits of doing this: 1. make vring_map_one_sg more simple, without calling vring_mapping_error to check the return value. 2. reduce one judgment of vq->use_dma_api. Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> --- drivers/virtio/virtio_ring.c | 37 +++++++++++++...

Rather than handing a scatterlist[] and out and in numbers to virtqueue_add_buf(), hand two separate ones which can be chained. I shall refrain from ranting about what a disgusting hack chained scatterlists are. I'll just note that this doesn't make things simpler (see diff). The scatterlists we use can be too large for the stack, so we put them in our device struct and reuse them. But in many cases we don't want to pay the cost of sg_init_table() as we d...

Rather than handing a scatterlist[] and out and in numbers to virtqueue_add_buf(), hand two separate ones which can be chained. I shall refrain from ranting about what a disgusting hack chained scatterlists are. I'll just note that this doesn't make things simpler (see diff). The scatterlists we use can be too large for the stack, so we put them in our device struct and reuse them. But in many cases we don't want to pay the cost of sg_init_table() as we d...

We used to have several callers which just used arrays. They're gone, so we can use sg_next() everywhere, simplifying the code. On my laptop, this slowed down vring_bench by 15%: vring_bench before: 936153354-967745359(9.44739e+08+/-6.1e+06)ns vring_bench after: 1061485790-1104800648(1.08254e+09+/-6.6e+06)ns However, a more realistic test using pktgen on a AMD FX(tm)-8320 saw a...

OK, so I've spent a few days benchmarking. Turns out 80% of virtio_add_buf cases are uni-directional (including the always-performance-sensitive networking code), and that gets no performance penalty (though tests with real networking would be appreciated!). I'm not reposting all the "convert driver to virtio_add_outbuf()" patches: just the scsi one which I didn't have

OK, so I've spent a few days benchmarking. Turns out 80% of virtio_add_buf cases are uni-directional (including the always-performance-sensitive networking code), and that gets no performance penalty (though tests with real networking would be appreciated!). I'm not reposting all the "convert driver to virtio_add_outbuf()" patches: just the scsi one which I didn't have

DMA-related logic is separated from the virtqueue_add_split() to one new function. DMA address will be saved as sg->dma_address if use_dma_api is true, then virtqueue_add_split() will use it directly. Unmap operation will be simpler. The purpose of this is to facilitate subsequent support to receive dma address mapped by drivers. Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> --- drivers/v...

DMA-related logic is separated from the virtqueue_add_split() to one new function. DMA address will be saved as sg->dma_address if use_dma_api is true, then virtqueue_add_split() will use it directly. Unmap operation will be simpler. The purpose of this is to facilitate subsequent support to receive dma address mapped by drivers. Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> --- drivers/v...

...rated from the virtqueue_add_split to prepare > for subsequent support for premapped. The patch seems to do more than what is described here. To simplify reviewers, I'd suggest to split this patch into three: 1) virtqueue_add_split_prepare() (could we have a better name?) 2) virtqueue_map_sgs() 3) virtqueue_add_split_vring() (Or only factor DMA parts out, I haven't gone through the reset of the patches) Thanks > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com> > --- > drivers/virtio/virtio_ring.c | 219 ++++++++++++++++++++++++----------- > 1 fil...

I resurrected these patches after prompting from Andy Lutomirski's recent patches. I put them on the back-burner because vring_bench had a 15% slowdown on my laptop: pktgen testing revealed a speedup, if anything, so I've cleaned them up. Rusty Russell (3): virtio_net: pass well-formed sgs to virtqueue_add_*() virtio_ring: assume sgs are always well-formed. virtio_ring: unify direct/indirect code paths. drivers/net/virtio_net.c | 5 +- drivers/virtio/virtio_ring.c | 185 +++++++++++++++---------------------------- 2 files changed, 69 insertions(+), 121 deletions(-) --...

I resurrected these patches after prompting from Andy Lutomirski's recent patches. I put them on the back-burner because vring_bench had a 15% slowdown on my laptop: pktgen testing revealed a speedup, if anything, so I've cleaned them up. Rusty Russell (3): virtio_net: pass well-formed sgs to virtqueue_add_*() virtio_ring: assume sgs are always well-formed. virtio_ring: unify direct/indirect code paths. drivers/net/virtio_net.c | 5 +- drivers/virtio/virtio_ring.c | 185 +++++++++++++++---------------------------- 2 files changed, 69 insertions(+), 121 deletions(-) --...

The only unusual thing about virtio's use of scatterlists is that two of the APIs accept scatterlists that might not be terminated. Using function pointers to handle this case is overkill; for_each_sg can do it. There's a small subtlely here: for_each_sg assumes that the provided count is correct, but, because of the way that virtio_ring handles multiple scatterlists at once, the count is only an upper bound if there is more than one scatterlist. This is easily solved by checking the sg po...

From: "Edgar E. Iglesias" <edgar.iglesias at xilinx.com> I'm trying to run rpmsg and remoteproc on the ZynqMP (arm64) but I'm hitting a DMA/mm error. The issue was discussed here: http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/333050.html Russel King pointed out that the arm64 is not doing anything wrong by returning vmapped memory (which is incompatible...

From: "Edgar E. Iglesias" <edgar.iglesias at xilinx.com> I'm trying to run rpmsg and remoteproc on the ZynqMP (arm64) but I'm hitting a DMA/mm error. The issue was discussed here: http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/333050.html Russel King pointed out that the arm64 is not doing anything wrong by returning vmapped memory (which is incompatible...

Add virtqueue_add_sgs which is more general than virtqueue_add_buf, which makes virtio-scsi and virtio-blk nicer, then add virtqueue_add_inbuf and virtqueue_add_outbuf which handle the more general case, and finally delete virtqueue_add_buf(). I'm hoping this will be the final post of the whole series, and it can...

Add virtqueue_add_sgs which is more general than virtqueue_add_buf, which makes virtio-scsi and virtio-blk nicer, then add virtqueue_add_inbuf and virtqueue_add_outbuf which handle the more general case, and finally delete virtqueue_add_buf(). I'm hoping this will be the final post of the whole series, and it can...

OK, this is (ab)uses some of Paolo's patches. The first 7 are candidates for this merge window (maybe), the rest I'm not so sure about. Thanks, Rusty. Paolo Bonzini (3): scatterlist: introduce sg_unmark_end virtio-blk: reorganize virtblk_add_req virtio-blk: use virtqueue_add_sgs on req path Rusty Russell (13): virtio_ring: virtqueue_add_sgs, to add multiple sgs. virtio-blk: use virtqueue_start_buf on bio path virtio_blk: remove nents member. virtio_ring: don't count element...

OK, this is (ab)uses some of Paolo's patches. The first 7 are candidates for this merge window (maybe), the rest I'm not so sure about. Thanks, Rusty. Paolo Bonzini (3): scatterlist: introduce sg_unmark_end virtio-blk: reorganize virtblk_add_req virtio-blk: use virtqueue_add_sgs on req path Rusty Russell (13): virtio_ring: virtqueue_add_sgs, to add multiple sgs. virtio-blk: use virtqueue_start_buf on bio path virtio_blk: remove nents member. virtio_ring: don't count element...