ioblksize.h

Absolute File Name:

/home/opencoverage/opencoverage/guest-scripts/coreutils/src/src/ioblksize.h

Line	Source	Count
1	/* I/O block size definitions for coreutils	-
2	Copyright (C) 1989-2018 Free Software Foundation, Inc.	-
3		-
4	This program is free software: you can redistribute it and/or modify	-
5	it under the terms of the GNU General Public License as published by	-
6	the Free Software Foundation, either version 3 of the License, or	-
7	(at your option) any later version.	-
8		-
9	This program is distributed in the hope that it will be useful,	-
10	but WITHOUT ANY WARRANTY; without even the implied warranty of	-
11	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the	-
12	GNU General Public License for more details.	-
13		-
14	You should have received a copy of the GNU General Public License	-
15	along with this program. If not, see <https://www.gnu.org/licenses/>. */	-
16		-
17	/* Include this file _after_ system headers if possible. */	-
18		-
19	/* sys/stat.h will already have been included by system.h. */	-
20	#include "stat-size.h"	-
21		-
22		-
23	/* As of May 2014, 128KiB is determined to be the minimium	-
24	blksize to best minimize system call overhead.	-
25	This can be tested with this script:	-
26		-
27	for i in $(seq 0 10); do	-
28	bs=$((10242*$i))	-
29	printf "%7s=" $bs	-
30	timeout --foreground -sINT 2 \	-
31	dd bs=$bs if=/dev/zero of=/dev/null 2>&1 \	-
32	\| sed -n 's/.* \([0-9.]* [GM]B\/s\)/\1/p'	-
33	done	-
34		-
35	With the results shown for these systems:	-
36	system #1: 1.7GHz pentium-m with 400MHz DDR2 RAM, arch=i686	-
37	system #2: 2.1GHz i3-2310M with 1333MHz DDR3 RAM, arch=x86_64	-
38	system #3: 3.2GHz i7-970 with 1333MHz DDR3, arch=x86_64	-
39	system #4: 2.20GHz Xeon E5-2660 with 1333MHz DDR3, arch=x86_64	-
40	system #5: 2.30GHz i7-3615QM with 1600MHz DDR3, arch=x86_64	-
41	system #6: 1.30GHz i5-4250U with 1-channel 1600MHz DDR3, arch=x86_64	-
42	system #7: 3.55GHz IBM,8231-E2B with 1066MHz DDR3, POWER7 revision 2.1	-
43		-
44	per-system transfer rate (GB/s)	-
45	blksize #1 #2 #3 #4 #5 #6 #7	-
46	------------------------------------------------------------------------	-
47	1024 .73 1.7 2.6 .64 1.0 2.5 1.3	-
48	2048 1.3 3.0 4.4 1.2 2.0 4.4 2.5	-
49	4096 2.4 5.1 6.5 2.3 3.7 7.4 4.8	-
50	8192 3.5 7.3 8.5 4.0 6.0 10.4 9.2	-
51	16384 3.9 9.4 10.1 6.3 8.3 13.3 16.8	-
52	32768 5.2 9.9 11.1 8.1 10.7 13.2 28.0	-
53	65536 5.3 11.2 12.0 10.6 12.8 16.1 41.4	-
54	131072 5.5 11.8 12.3 12.1 14.0 16.7 54.8	-
55	262144 5.7 11.6 12.5 12.3 14.7 16.4 40.0	-
56	524288 5.7 11.4 12.5 12.1 14.7 15.5 34.5	-
57	1048576 5.8 11.4 12.6 12.2 14.9 15.7 36.5	-
58		-
59		-
60	Note that this is to minimize system call overhead.	-
61	Other values may be appropriate to minimize file system	-
62	or disk overhead. For example on my current GNU/Linux system	-
63	the readahead setting is 128KiB which was read using:	-
64		-
65	file="."	-
66	device=$(df --output=source --local "$file" \| tail -n1)	-
67	echo $(( $(blockdev --getra $device) * 512 ))	-
68		-
69	However there isn't a portable way to get the above.	-
70	In the future we could use the above method if available	-
71	and default to io_blksize() if not.	-
72	*/	-
73	enum { IO_BUFSIZE = 128*1024 };	-
74	static inline size_t	-
75	io_blksize (struct stat sb)	-
76	{	-
77	return MAX (IO_BUFSIZE, ST_BLKSIZE (sb)); executed 13274 times by 5 tests: `return ((( IO_BUFSIZE )>( ((0 < (sb).st_blksize && (sb).st_blksize <= ((size_t)-1) / 8 + 1) ? (sb).st_blksize : 512 ) ))?( IO_BUFSIZE ):( ((0 < (sb).st_blksize && (sb).st_blksize <= ((size_t)-1) / 8 + 1) ? (sb).st_blksize : 512 ) )) ;` Executed by: cat cp ginstall mv split	13274
78	}	-

Line

Source

Count

/* I/O block size definitions for coreutils

This program is free software: you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 3 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program. If not, see <https://www.gnu.org/licenses/>. */

/* Include this file _after_ system headers if possible. */

/* sys/stat.h will already have been included by system.h. */

#include "stat-size.h"

/* As of May 2014, 128KiB is determined to be the minimium

blksize to best minimize system call overhead.

This can be tested with this script:

for i in $(seq 0 10); do

bs=$((1024*2**$i))

printf "%7s=" $bs

timeout --foreground -sINT 2 \

dd bs=$bs if=/dev/zero of=/dev/null 2>&1 \

| sed -n 's/.* $[0-9.]* [GM]B\/s$/\1/p'

done

With the results shown for these systems:

system #1: 1.7GHz pentium-m with 400MHz DDR2 RAM, arch=i686

system #2: 2.1GHz i3-2310M with 1333MHz DDR3 RAM, arch=x86_64

system #3: 3.2GHz i7-970 with 1333MHz DDR3, arch=x86_64

system #4: 2.20GHz Xeon E5-2660 with 1333MHz DDR3, arch=x86_64

system #5: 2.30GHz i7-3615QM with 1600MHz DDR3, arch=x86_64

system #6: 1.30GHz i5-4250U with 1-channel 1600MHz DDR3, arch=x86_64

system #7: 3.55GHz IBM,8231-E2B with 1066MHz DDR3, POWER7 revision 2.1

per-system transfer rate (GB/s)

blksize #1 #2 #3 #4 #5 #6 #7

------------------------------------------------------------------------

1024 .73 1.7 2.6 .64 1.0 2.5 1.3

2048 1.3 3.0 4.4 1.2 2.0 4.4 2.5

4096 2.4 5.1 6.5 2.3 3.7 7.4 4.8

8192 3.5 7.3 8.5 4.0 6.0 10.4 9.2

16384 3.9 9.4 10.1 6.3 8.3 13.3 16.8

32768 5.2 9.9 11.1 8.1 10.7 13.2 28.0

65536 5.3 11.2 12.0 10.6 12.8 16.1 41.4

131072 5.5 11.8 12.3 12.1 14.0 16.7 54.8

262144 5.7 11.6 12.5 12.3 14.7 16.4 40.0

524288 5.7 11.4 12.5 12.1 14.7 15.5 34.5

1048576 5.8 11.4 12.6 12.2 14.9 15.7 36.5

Note that this is to minimize system call overhead.

Other values may be appropriate to minimize file system

or disk overhead. For example on my current GNU/Linux system

the readahead setting is 128KiB which was read using:

file="."

device=$(df --output=source --local "$file" | tail -n1)

echo $(( $(blockdev --getra $device) * 512 ))

However there isn't a portable way to get the above.

In the future we could use the above method if available

and default to io_blksize() if not.

enum { IO_BUFSIZE = 128*1024 };

static inline size_t

io_blksize (struct stat sb)

{

return MAX (IO_BUFSIZE, ST_BLKSIZE (sb));

executed 13274 times by 5 tests:

return ((( IO_BUFSIZE )>( ((0 < (sb).st_blksize && (sb).st_blksize <= ((size_t)-1) / 8 + 1) ? (sb).st_blksize : 512 ) ))?( IO_BUFSIZE ):( ((0 < (sb).st_blksize && (sb).st_blksize <= ((size_t)-1) / 8 + 1) ? (sb).st_blksize : 512 ) )) ;

Executed by:

cat
cp
ginstall
mv
split

13274

}

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