From: "H. Peter Anvin" <hpa@zytor.com>
To: Denys Vlasenko <dvlasenk@redhat.com>, Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Borislav Petkov <bp@alien8.de>,
Andy Lutomirski <luto@amacapital.net>,
Frederic Weisbecker <fweisbec@gmail.com>,
Alexei Starovoitov <ast@plumgrid.com>,
Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: Deinline cpuid_eax and friends
Date: Wed, 06 May 2015 11:59:40 -0700 [thread overview]
Message-ID: <554A649C.8070605@zytor.com> (raw)
In-Reply-To: <1430932057-26574-1-git-send-email-dvlasenk@redhat.com>
On 05/06/2015 10:07 AM, Denys Vlasenko wrote:
> cpuid_e{a,b,c,d}x() functions compile to 44 bytes of machine code each.
> On x86 allyesconfig build they have 48 callsites.
> Deinlining all four of them shrinks kernel by about 1k:
>
> text data bss dec hex filename
> 82434909 22255384 20627456 125317749 7783275 vmlinux.before
> 82433898 22255384 20627456 125316738 7782e82 vmlinux
>
> Speed impact: CPUID instruction takes from 50 to 350+ cycles,
> call overhead is negligible in comparison.
How on Earth does it make 44 bytes? Is this due to paravirt_fail?
-hpa
next prev parent reply other threads:[~2015-05-06 19:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-06 17:07 [PATCH] x86: Deinline cpuid_eax and friends Denys Vlasenko
2015-05-06 18:59 ` H. Peter Anvin [this message]
2015-05-06 19:09 ` Denys Vlasenko
2015-05-06 20:41 ` H. Peter Anvin
2015-05-07 8:57 ` Denys Vlasenko
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