Gentoo Archives: gentoo-performance

From: "Ervin Németh" <ervin.nemeth@××××.hu>
To: gentoo-performance@l.g.o
Subject: Re: [gentoo-performance] inline considered harmful
Date: Thu, 22 Jul 2004 09:20:23
Message-Id: 40FF86D0.5090101@niif.hu
In Reply to: [gentoo-performance] inline considered harmful by Mario Domenech Goulart
1 Mario Domenech Goulart wrote:
2 > There's an interesting discussion in the OpenBSD mailing
3 > list about the use of inline.
4
5 There is no such thing as "best optimization". Some optimization
6 techniques tend to show better performance on the average, but given a
7 specific code, the same technique can fail dramatically.
8
9 Inlining makes the code faster if the called function is small
10 (preferably smaller than a cache-line), and called only a few times. No
11 inlining will result in faster code if the function is large (at least
12 one complete cache-line is used), and that function has a good chance to
13 be already in the cache when called.
14
15 Also inlined functions allow the block-reordering code to do interesting
16 things. Block-reordering was introduced in gcc3, BSDs are using
17 gcc-2.95, AFAIK.
18
19 So far the facts.
20
21 Now the manual says that for gcc the inline-limit is 600 bytes, compared
22 to the 32-128 byte cache line size of the x86 CPUs. It could be worth to
23 try lower numbers with inline-functions...
24
25
26 /Ervin
27
28 --
29 gentoo-performance@g.o mailing list

Replies

Subject Author
Re: [gentoo-performance] inline considered harmful Dylan Carlson <absinthe@g.o>
Re: [gentoo-performance] inline considered harmful Bart Alewijnse <scarfboy@×××××.com>