> > [note: something is wrong with your email client, your previous reply appears to > be in HTML] > Sorry, fixed it. >>> That is a good idea, lot of drivers are waiting for completion which can >>> be signalled from hardirq, this would also reduce the hops we have and >>> help improve latency a bit. On the downside, some controllers provide >>> error information, which would need to be dealt with. >> >> >> I am not an expert in dma subsystem, but by using completion from >> Hardirq context be a concern? Especially with latency. > > I don't see how: to the task waiting for the completion, there should > be no difference, and for the irq handler sending it, it just avoids > a few cycles going into softirq context. Thanks for clarification. If I have understood it correctly, your suggestion is to move the current Callback mechanism out to dmaengine as a generic helper function And introduce completion in dma_async_tx_descriptor to handle what Tasklets currently do. Thanks. > >>> Yes that would be a very reasonable mechanism, thanks for the >>> suggestions. >> >> I have started working on the idea of global softirq. A RFC should be ready >> For review soon. > > Ok, thanks! > > Arnd
