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Re: [PATCH 1/2] Add framework for tunables
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Siddhesh Poyarekar <siddhesh at sourceware dot org>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Sun, 3 Jul 2016 10:41:40 -0700
- Subject: Re: [PATCH 1/2] Add framework for tunables
- Authentication-results: sourceware.org; auth=none
- References: <1467479562-11357-1-git-send-email-siddhesh at sourceware dot org> <1467479562-11357-2-git-send-email-siddhesh at sourceware dot org> <CAMe9rOqhHyGJb-knN48pyDJJxVqOF=yxFHj_RzL3tnH9jJqvVQ at mail dot gmail dot com> <20160703171343 dot GM7564 at devel dot intra dot reserved-bit dot com>
On Sun, Jul 3, 2016 at 10:13 AM, Siddhesh Poyarekar
<siddhesh@sourceware.org> wrote:
> On Sun, Jul 03, 2016 at 07:44:25AM -0700, H.J. Lu wrote:
>> > +
>> > +/* Compare environment names, bounded by the name hardcoded in glibc. */
>> > +static bool
>> > +is_name (const char *orig, const char *envname)
>> > +{
>> > + for (;*orig != '\0' && *envname != '\0'; envname++, orig++)
>> > + if (*orig != *envname)
>> > + break;
>> > +
>> > + /* The ENVNAME is immediately followed by a value. */
>> > + if (*orig == '\0' && *envname == '=')
>> > + return true;
>> > + else
>> > + return false;
>> > +}
>>
>> Can you add the length parameter to is_name and make is_name
>> processor specific so that misaligned short/int/long long load can
>> be used, similar to equal in
>
> Will it really make that much of an impact? These will be really
> short comparisons (less than 16 bytes in most cases) and will really
> only happen once during startup.
>
> Maybe we could do it as an addon patch if the tunables initialization
> really turns out to be that much of a bottleneck.
>
Sure.
--
H.J.