Hi Huacai,
On Wed, Sep 05, 2018 at 05:33:01PM +0800, Huacai Chen wrote:
> New Loongson-3 (Loongson-3A R2, Loongson-3A R3, and newer) has SFB
> (Store Fill Buffer) which can improve the performance of memory access.
> Now, SFB enablement is controlled by CONFIG_LOONGSON3_ENHANCEMENT, and
> the generic kernel has no benefit from SFB (even it is running on a new
> Loongson-3 machine). With this patch, we can enable SFB at runtime by
> detecting the CPU type (the expense is war_io_reorder_wmb() will always
> be a 'sync', which will hurt the performance of old Loongson-3).
This looks unchanged since v3, and I didn't see a response to my email
here:
https://marc.info/?l=linux-mips&m=153248530725061&w=2
I still haven't seen any explanation for why you can't just do this as a
one-liner in C, the same way we enable tons of other CPU features during
cpu_probe().
I'm not saying I'll never accept the assembly version, but I want an
explanation for why it's necessary first. If that's not something you
can give, at least describe in the commit message what goes wrong when
you try to do it in C as justification for not doing it that way.
Thanks,
Paul
