Re: [PATCH 05/26] perf tools: Add build_id__is_defined function

[Jiri Olsa]

On Mon, Sep 14, 2020 at 01:03:18PM -0300, Arnaldo Carvalho de Melo wrote:

SNIP

> +       if (!ns) {
> +               status = NVME_SC_INVALID_NS | NVME_SC_DNR;
> +               goto out;
> +       }
> +
> +       if (memchr_inv(&ns->uuid, 0, sizeof(ns->uuid))) {
> +               status = nvmet_copy_ns_identifier(req, NVME_NIDT_UUID,
> +                                                 NVME_NIDT_UUID_LEN,
> +                                                 &ns->uuid, &off);
> +               if (status)
> +                       goto out_put_ns;
> +       }
> 
> More:
> 
> [acme@five perf]$ find arch/ -type f | xargs grep memchr_inv
> arch/x86/kernel/fpu/xstate.c: if (memchr_inv(hdr->reserved, 0, 
> sizeof(hdr->reserved)))
> arch/x86/mm/init_64.c:                        if (!memchr_inv(page_addr, 
> PAGE_INUSE, PAGE_SIZE)) {
> arch/x86/mm/init_64.c:                                if 
> (!memchr_inv(page_addr, PAGE_INUSE,
> arch/x86/mm/init_64.c:                                if 
> (!memchr_inv(page_addr, PAGE_INUSE,
> arch/s390/mm/vmem.c:  return !memchr_inv(page, PAGE_UNUSED, PMD_SIZE);
> arch/powerpc/platforms/powermac/nvram.c:      if (memchr_inv(base, 0xff, 
> NVRAM_SIZE)) {
> arch/powerpc/platforms/powermac/nvram.c:      if (memchr_inv(base, 0xff, 
> NVRAM_SIZE)) {
> [acme@five perf]$

nice, another stricg.c candidate ;-)

I can add the is_zeroed function and we can speed it up
for above archs later

thanks,
jirka