From: Heiner Kallweit <hkallweit1@gmail.com>
To: Eric Dumazet <edumazet@google.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
David Miller <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Remove __napi_schedule_irqoff?
Date: Sat, 17 Oct 2020 15:45:57 +0200 [thread overview]
Message-ID: <01af7f4f-bd05-b93e-57ad-c2e9b8726e90@gmail.com> (raw)
When __napi_schedule_irqoff was added with bc9ad166e38a
("net: introduce napi_schedule_irqoff()") the commit message stated:
"Many NIC drivers can use it from their hard IRQ handler instead of
generic variant."
It turned out that this most of the time isn't safe in certain
configurations:
- if CONFIG_PREEMPT_RT is set
- if command line parameter threadirqs is set
Having said that drivers are being switched back to __napi_schedule(),
see e.g. patch in [0] and related discussion. I thought about a
__napi_schedule version checking dynamically whether interrupts are
disabled. But checking e.g. variable force_irqthreads also comes at
a cost, so that we may not see a benefit compared to calling
local_irq_save/local_irq_restore.
If more or less all users have to switch back, then the question is
whether we should remove __napi_schedule_irqoff.
Instead of touching all users we could make __napi_schedule_irqoff
an alias for __napi_schedule for now.
[0] https://lkml.org/lkml/2020/10/8/706
next reply other threads:[~2020-10-17 13:51 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-17 13:45 Heiner Kallweit [this message]
2020-10-17 23:29 ` Remove __napi_schedule_irqoff? Jakub Kicinski
2020-10-18 8:02 ` Eric Dumazet
2020-10-18 8:20 ` Heiner Kallweit
2020-10-18 17:19 ` Jakub Kicinski
2020-10-18 17:57 ` Heiner Kallweit
2020-10-18 18:02 ` Jakub Kicinski
2020-10-19 10:33 ` Thomas Gleixner
2020-10-19 17:55 ` Jakub Kicinski
2020-10-23 19:21 ` Grygorii Strashko
2020-10-18 9:55 ` Thomas Gleixner
2020-10-18 11:57 ` Heiner Kallweit
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