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| author | Maxim Sobolev <sobomax@FreeBSD.org> | 2018-11-29 19:28:01 +0000 |
|---|---|---|
| committer | Maxim Sobolev <sobomax@FreeBSD.org> | 2018-11-29 19:28:01 +0000 |
| commit | dead7b5e47d14f6560c5be40e673664ba20c670f (patch) | |
| tree | d35261be8adc5986baf73412030722df77b9435a /bin/dd/dd.h | |
| parent | 7d2b0bd7d78a05f57adb96cc73a605d05938a037 (diff) | |
| download | src-dead7b5e47d14f6560c5be40e673664ba20c670f.tar.gz src-dead7b5e47d14f6560c5be40e673664ba20c670f.zip | |
Replace hand-crafted naive byte-by-byte zero block detection routine
with macro based around memcmp(). The latter is expected to be some
8 times faster on a modern 64-bit architectures.
In practice, throughput of doing conv=sparse from /dev/zero to /dev/null
went up some 5-fold here from 1.9GB/sec to 9.7GB/sec with this change
(bs=128k).
MFC after: 2 weeks
Notes
Notes:
svn path=/head/; revision=341257
Diffstat (limited to 'bin/dd/dd.h')
| -rw-r--r-- | bin/dd/dd.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/bin/dd/dd.h b/bin/dd/dd.h index 0f7c680a6ee0..8090252923fd 100644 --- a/bin/dd/dd.h +++ b/bin/dd/dd.h @@ -103,3 +103,7 @@ typedef struct { #define C_PROGRESS 0x40000000 #define C_PARITY (C_PAREVEN | C_PARODD | C_PARNONE | C_PARSET) + +#define BISZERO(p, s) ((s) > 0 && *((const char *)p) == 0 && !memcmp( \ + (const void *)(p), (const void *) \ + ((const char *)p + 1), (s) - 1)) |