Bug 2659

Summary:	Perform pattern lookups without strcmp
Product:	fontconfig	Reporter:	Ross Burton <ross>
Component:	library	Assignee:	Keith Packard <keithp>
Status:	RESOLVED FIXED	QA Contact:
Severity:	normal
Priority:	high	CC:	bugzilla
Version:	2.2
Hardware:	x86 (IA32)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	The patch Make pattern values static Make all values static

Description Ross Burton 2005-03-07 04:06:45 UTC

Attached is a patch which will ensure every .object in a FcPattern has gone
though FcStaticObjectName(), so that lookup can then be a binary search based on
pointer compare rather than string compare.

This saves both memory:

before: still reachable: 1279114 bytes in 22542 blocks.
 after: still reachable: 1254887 bytes in 21980 blocks.

but also processor cycles, as strcmp() is called far less:

before: 42,567,584  ???:strcmp [/lib/tls/libc-2.3.2.so]
 after: 36,220,128  ???:strcmp [/lib/tls/libc-2.3.2.so]

(from running callgrind on the GTK+ font selector)

Comment 1 Ross Burton 2005-03-07 04:07:04 UTC

Created attachment 2028 [details] [review]
The patch

Comment 2 Ross Burton 2005-03-07 04:10:53 UTC

Obviously the next step is to find where the rest of the strcmp() are being
called, and to possibly apply the same algorithm to *all* strings going into the
patterns.

Comment 3 Ross Burton 2005-03-30 07:03:45 UTC

I did a quick hack which changed FcValueSave on strings from a call to FcStrCopy
into call to FcObjectStaticName.  Running fc-list with ~400 fonts in Valgrind
gives me this.

Before: malloc/free: 68325 allocs, 66665 frees, 3506738 bytes allocated.
 After: malloc/free: 59101 allocs, 57441 frees, 3376916 bytes allocated.

Comment 4 Ross Burton 2005-03-31 08:22:03 UTC

Created attachment 2274 [details] [review]
Make pattern values static

Applying both the first patch and this patch will result in all strings in
patterns being made static.  This helps as it reduces duplication of values:
for example on my system there are 464 copies of the string "Adobe" and 330
copies of the string "Bold".

Comment 5 Ross Burton 2005-03-31 11:17:33 UTC

I've just committed the first patch, making the "object" variables static.  I'll
work on the values patch more, as I'm not happy with it.

Comment 6 Ross Burton 2005-04-01 04:24:14 UTC

Created attachment 2283 [details] [review]
Make all values static

This patch puts all FcPattern string values through FcObjectStaticName, and
ignores strings when the values are being destroyed.

Comment 7 Patrick Lam 2006-02-22 02:05:02 UTC

All .object values are now static after the mmap goodness.

Comment 8 Patrick Lam 2006-02-22 02:05:18 UTC

Marking FIXED.

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