On Wed, 8 Sep 2021 11:34:27 -0700 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > I'm dropping this one just to be consistent, although for memset() > it's possibly a bit more reasonable to fall back on some default. > > But probably not. memcpy and memset really are *so* special that these > generic versions should be considered to be "stupid placeholders for > bringup, and nothing more". > > On Tue, Sep 7, 2021 at 7:58 PM Andrew Morton > <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > On a RISC-V machine the speed goes from 140 Mb/s to 241 Mb/s, and > > this the binary size increase according to bloat-o-meter: > > I also react to the benchmark numbers: RISC-V already has > > #define __HAVE_ARCH_MEMSET > #define __HAVE_ARCH_MEMCPY > #define __HAVE_ARCH_MEMMOVE > > in its <asm/string.h> file, so these are just odd. > > Did you benchmark these generic functions on their own, rather than > the ones that actually get *used*? > > Linus I benchmarked against the generic routines. The RISC-V specific are even slower than the generic ones, because generates lot of unaligned accesses. That was the whole point of the series initially. These C routines should have replaced the risc-v specific assembly ones, but then it was proposed to use them as generic: https://lore.kernel.org/linux-riscv/YNChl0tkofSGzvIX@xxxxxxxxxxxxx/ -- per aspera ad upstream
