On Tue, 2015-05-19 at 16:56 +0100, One Thousand Gnomes wrote:
> On Tue, 19 May 2015 07:46:58 +0100 David Woodhouse <dw...@infradead.org>
> wrote:
> > On Mon, 2015-05-18 at 17:07 -0700, Joe Perches wrote:
> > > changed dmi_strmatch.substr from char * to char[79];
> > >
> > > Changing it back to const char * would shrink an x86-64
> > > defconfig more than 100KB.
> > >
> > > $ size vmlinux.old vmlinux.new
> > > text data bss dec hex filename
> > > 11941725 1825624 1085440 14852789 e2a2b5 vmlinux.old
> > > 11921172 1730648 1085440 14737260 e0df6c vmlinux.new
>
> What percentage of those are __initdata ?
old: 17 .init.data 000876b0 ffffffff81f9e000 0000000001f9e000 0139e000
2**12
new: 17 .init.data 000711b0 ffffffff81f9d000 0000000001f9d000 0139d000
2**12
.init.data: 0x876b0 - 0x711b0 = 0x16500 (91392)
vmlinux: 14852789 - 14737260 = 115529
so there's ~25KB delta that's not .init.data.
The longest DMI_MATCH substr I found was 40 chars, so
there's some value in reducing the substr size of 79
to something shorter like 47 to reduce 80*4=320 to
48*4=192 per use.
$ grep-2.5.4 -rP --include=*.[ch]
"\bDMI_(?:EXACT_)?MATCH\s*\(\s*\w+\s*,\s*\"[^\"]*" *| \
grep -oh '"[^"]*"' | \
sed 's/"//g' | sort | uniq | \
awk '{print length($0), " ", $0}'| \
sort -rn | head -10
39 Matsushita Electric Industrial Co.,Ltd.
35 ASUS PR-DLS ACPI BIOS Revision 1010
34 Micro-Star International Co., Ltd.
34 Award Software International, Inc.
34 900X3C/900X3D/900X3E/900X4C/900X4D
34 370R4E/370R4V/370R5E/3570RE/370R5V
33 MICRO-STAR INTERNATIONAL CO., LTD
32 MV85010A.86A.0016.P07.0201251536
32 MO81010A.86A.0008.P04.0004170800
32 ASUS A7V ACPI BIOS Revision 1007
Changing substr from 79 to 47 reduces .init.data a bit
(different -next version)
old: 17 .init.data 00081718 ffffffff81f84000 0000000001f84000 01384000
2**12
new: 17 .init.data 00076598 ffffffff81f84000 0000000001f84000 01384000
2**12
.init.data: 0x81718 - 0x76598 = 0xb180 (45440)
Unless/until modpost is updated, maybe this patch is OK:
---
include/linux/mod_devicetable.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 3bfd567..279f1be 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -462,7 +462,11 @@ enum dmi_field {
struct dmi_strmatch {
unsigned char slot:7;
unsigned char exact_match:1;
- char substr[79];
+#ifdef CONFIG_MODULES
+ char substr[47];
+#else
+ const char *substr;
+#endif
};
struct dmi_system_id {
--
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