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Date:   Mon, 14 Sep 2020 22:49:28 +0200
From:   Jiri Olsa <jolsa@redhat.com>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Michael Petlan <mpetlan@redhat.com>,
        Song Liu <songliubraving@fb.com>,
        "Frank Ch. Eigler" <fche@redhat.com>,
        Ian Rogers <irogers@google.com>,
        Stephane Eranian <eranian@google.com>,
        Alexey Budankov <alexey.budankov@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCH 05/26] perf tools: Add build_id__is_defined function
Message-ID: <20200914204928.GA1714160@krava>
References: <20200913210313.1985612-1-jolsa@kernel.org>
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 <20200914160318.GG160517@kernel.org>
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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