Hi Jason,
On Mon, Nov 16, 2015, at 21:58, Jason A. Donenfeld wrote:
> Hi David,
>
> On Mon, Nov 16, 2015 at 9:32 PM, David Miller <da...@davemloft.net>
> wrote:
> > Network device driver transmit executes with software interrupts
> > disabled.
> >
> > Therefore on x86, you cannot use the FPU.
>
> That is extremely problematic for me. Is there a way to make this not
> so? A driver flag that would allow this?
>
> Also - how come it irq_fpu_usable() is true when using TCP but not
> when using UDP?
>
> Further, irq_fpu_usable() doesn't only check for interrupts. There are
> two other conditions that allow the FPU's usage, from
> arch/x86/kernel/fpu/core.c:
>
> bool irq_fpu_usable(void)
> {
> return !in_interrupt() ||
> interrupted_user_mode() ||
> interrupted_kernel_fpu_idle();
> }
Use the irqsoff tracer to find the problematic functions which disable
interrupts and try to work around it in case of UDP. This could benefit
the whole stack.
Bye,
Hannes
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
