On sam., 2016-02-27 at 15:33 -0800, Peter Hurley wrote: > On 02/27/2016 03:04 PM, David Miller wrote: > > From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> > > Date: Sat, 27 Feb 2016 12:29:39 -0800 > > > >> Not really. softirq raised from interrupt context will always execute > >> on this cpu and not in ksoftirqd, unless load forces softirq loop abort. > > > > That guarantee never was specified. > > ?? > > Neither is running network socket servers at normal priority as if they're > higher priority than softirq. > > > > Or are you saying that by design, on a system under load, your UART > > will not function properly? > > > > Surely you don't mean that. > > No, that's not what I mean. > > What I mean is that bypassing the entire SOFTIRQ priority so that > sshd can process one network packet makes a mockery of the point of softirq. > > This hack to workaround NET_RX looping over-and-over-and-over affects every > subsystem, not just one uart. > > HI, TIMER, BLOCK; all of these are skipped: that's straight-up, a bug. No idea what you talk about. All pending softirq interrupts are processed. _Nothing_ is skipped. Really, your system stability seems to depend on a completely undocumented behavior of linux kernels before linux-3.8 If I understood, you expect that a tasklet activated from a softirq handler is run from the same __do_softirq() loop. This never has been the case. My change simply triggers the bug in your driver earlier. As David pointed out, your bug should trigger the same on a loaded machine, even if you revert my patch. I honestly do not know why you arm a tasklet from NET_RX, why don't you simply process this directly, so that you do not rely on some scheduler decision ? -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
