On 5/3/24 12:39, Christian Marangi wrote:
On Fri, May 03, 2024 at 12:07:45PM -0700, Florian Fainelli wrote:On 5/3/24 06:54, Christian Marangi wrote:Drop redundant boot_cpu_type in arch_sync_dma_for_cpu_all. These needs to be parsed only once and we can make use of bmips_rac_flush_disable to disable RAC flush on unsupported CPU. Set this value in bmips_cpu_setup for unsupported CPU to skip this redundant check every time DMA needs to be synced. Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>You are taking a shortcut that is reasonable in premise, but keying off the bmips_rac_flush_disable is IMHO misleading. The RAC is enabled in the BMIPS5000 and BMIPS5200 cores, just it does not need SW management unlike earlier cores. If you renamed it to bmips_rac_flush_needed that might be more compelling. Also, the other reason is that on a kernel that was configured for supporting only BMIPS5000 and BMIPS5200 CPUs, I think we could get some decent dead code elimination of the boot_cpu_type() check, which would not be the case.I was a bit confused by the last part, should I drop this or just rename the variable? Cause I think for kernel that support ONLY those CPU I guess the DMA function will be optimized anyway since the bool will always be false I guess?
I don't think it can be optimized, I would drop that patch. This is a hot-path and so any optimization is welcome.
-- Florian
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