Hello Greg, On Tue, Jun 20, 2023 at 04:59:18PM +0200, Greg Kroah-Hartman wrote: > On Tue, Jun 20, 2023 at 04:47:10PM +0200, Linux regression tracking (Thorsten Leemhuis) wrote: > > On 24.05.23 15:07, Stefan Wahren wrote: > > > > > > Am 23.05.23 um 21:44 schrieb Sergey Organov: > > >> "Linux regression tracking (Thorsten Leemhuis)" > > >> <regressions@xxxxxxxxxxxxx> writes: > > >> > > >> Solving this would need to identify the cause of interrupts being > > >> disabled for prolonged times, and nobody volunteered to investigate this > > >> further. One suspect, the Linux serial console, has been likely excluded > > >> already though, as not actually being in use for printk() output. > > >> > > > > > > I don't think that we can exclude the serial console as a whole, i never > > > made such a observation. But at least we can exclude kernel logging on > > > the debug UART. > > > > Stefan, just wondering: was this ever addressed upstream? I assume it's > > not, just wanted to be sure. > > > > I'm a bit unsure what to do with this and consider asking Greg for > > advice, as he applied the patch. On one hand it's *IMHO* clearly a > > regression (but for the record, some people involved in the discussion > > claim it's not). OTOH the culprit was applied more than a year ago now, > > so reverting it might cause more trouble than it's worth at this point, > > as that could lead to regressions for other users. > > I'll be glad to revert this, but for some reason I thought that someone > was working on a "real fix" here. Stefan, is that not the case? Sergey Organov already said something similar, but not very explicit: With the current understanding reverting said commit is wrong. It is expected that the commit increases irq latency for imx-serial a bit for the benefit of less interrupts and so serves the overall system performance. That this poses a problem only means that on the reporter's machine there is already an issue that results in a longer period with disabled irqs. While reverting the imx-serial commit would (maybe) solve that, the actual problem is the other issue that disables preemption for a longer timespan. So TL;DR: Please don't revert the imx-serial patch. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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