Messages in this thread | | | Subject | Re: Softirq priority inversion from "softirq: reduce latencies" | From | Peter Hurley <> | Date | Sat, 27 Feb 2016 15:33:58 -0800 |
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On 02/27/2016 03:04 PM, David Miller wrote: > From: Peter Hurley <peter@hurleysoftware.com> > 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.
Regards, Peter Hurley
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