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Include <string.h> in "mmap is worth using" test (#375)

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The "mmap is worth using" test uses memcpy but doesn't include the
system header in which that function is declared, leading to
"error: implicitly declaring library function 'memcpy'" when trying
to compile the test. By including the header, the test can now
compile and run as intended.

On macOS, the result is still negative. The test seems to time
using mmap and another method and only picks mmap if it's faster.
Editing the test to print out timing information on a few runs, I
see that mmap is 2–3✕ slower than the other method:

$ for i in $(seq 1 5); do ./mmap_worth_using; done
/* mmtm=11 rdtm=3 */
/* 4*mmtm=44 3*rdtm=9 */
/* 4*mmtm=44 5*rdtm=15 */
/* mmtm=9 rdtm=5 */
/* 4*mmtm=36 3*rdtm=15 */
/* 4*mmtm=36 5*rdtm=25 */
/* mmtm=10 rdtm=4 */
/* 4*mmtm=40 3*rdtm=12 */
/* 4*mmtm=40 5*rdtm=20 */
/* mmtm=12 rdtm=4 */
/* 4*mmtm=48 3*rdtm=12 */
/* 4*mmtm=48 5*rdtm=20 */
/* mmtm=12 rdtm=4 */
/* 4*mmtm=48 3*rdtm=12 */
/* 4*mmtm=48 5*rdtm=20 */
This commit is contained in:
Ryan Schmidt 2021-12-12 14:29:46 -06:00 committed by Martijn Dekker
parent 0eb857041d
commit b31fe887b8
1 changed files with 2 additions and 1 deletions
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3
src/lib/libast/features/mmap
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@ -219,12 +219,13 @@ tst mmap_devzero note{ use mmap on /dev/zero to get raw memory }end execute{
}
}end
tst note{ mmap is worth using }end output{
tst note{ mmap is fast enough to be worth using }end output{
#if !_lib_mmap
(
#endif
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>