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Some comments about the use of posix_advise().

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Andrea Mazzoleni 2011-03-29 18:27:25 +02:00
parent 81f14d1dfb
commit 637789d11b
3 changed files with 20 additions and 3 deletions
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1
HISTORY
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@ -3,6 +3,7 @@ SnapRAID HISTORY
0.3 2011/4
==========
* Better ETA estimation.
* Added support for OpenSSL crypto library to use its optimized MD5 implementation.
* Added test vector for MD5.
* Added a speed test option for MD5.

8
handle.c
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@ -256,6 +256,11 @@ int handle_read(struct snapraid_handle* handle, struct snapraid_block* block, un
return -1;
}
/* Here isn't needed to call posix_fadvise(..., POSIX_FADV_DONTNEED) because */
/* we already advised sequential access with POSIX_FADV_SEQUENTIAL. */
/* In Linux 2.6.33 it's enough to ensure that data is not kept in the cache. */
/* Better to do nothing and save a syscall for each block. */
return read_size;
}
@ -284,6 +289,9 @@ int handle_write(struct snapraid_handle* handle, struct snapraid_block* block, u
return -1;
}
/* Here doesn't make sense to call posix_fadvise(..., POSIX_FADV_DONTNEED) because */
/* at this time the data is still in not yet written and it cannot be discharged. */
return 0;
}

14
parity.c
View file

@ -143,9 +143,9 @@ int parity_sync(const char* path, int f)
#if HAVE_FSYNC
int ret;
/* ensure that data changes are written to disk */
/* this is required to ensure that parity is more updated than content */
/* in case of a system crash */
/* Ensure that data changes are written to disk. */
/* This is required to ensure that parity is more updated than content */
/* in case of a system crash. */
ret = fsync(f);
if (ret != 0) {
fprintf(stderr, "Error synching parity file '%s'. %s.\n", path, strerror(errno));
@ -202,6 +202,9 @@ int parity_write(const char* path, int f, block_off_t pos, unsigned char* block_
return -1;
}
/* Here doesn't make sense to call posix_fadvise(..., POSIX_FADV_DONTNEED) because */
/* at this time the data is still in not yet written and it cannot be discharged. */
return 0;
}
@ -227,6 +230,11 @@ int parity_read(const char* path, int f, block_off_t pos, unsigned char* block_b
return -1;
}
/* Here isn't needed to call posix_fadvise(..., POSIX_FADV_DONTNEED) because */
/* we already advised sequential access with POSIX_FADV_SEQUENTIAL. */
/* In Linux 2.6.33 it's enough to ensure that data is not kept in the cache. */
/* Better to do nothing and save a syscall for each block. */
return block_size;
}