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Merge branch '1.0-maint' of github.com:borgbackup/borg into 1.0-maint

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This commit is contained in:
Thomas Waldmann 2016-04-16 02:36:06 +02:00
commit 813dbc4d25
1 changed files with 23 additions and 2 deletions
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25
borg/_chunker.c
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@ -41,6 +41,7 @@ static uint32_t table_base[] =
#define BARREL_SHIFT(v, shift) ( ((v) << shift) | ((v) >> (32 - shift)) )
size_t pagemask;
static uint32_t *
buzhash_init_table(uint32_t seed)
@ -130,6 +131,7 @@ chunker_fill(Chunker *c)
{
ssize_t n;
off_t offset, length;
int overshoot;
PyObject *data;
memmove(c->data, c->data + c->last, c->position + c->remaining - c->last);
c->position -= c->last;
@ -157,14 +159,33 @@ chunker_fill(Chunker *c)
}
length = c->bytes_read - offset;
#if ( ( _XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L ) && defined(POSIX_FADV_DONTNEED) )
// Only do it once per run.
if (pagemask == 0)
pagemask = getpagesize() - 1;
// We tell the OS that we do not need the data that we just have read any
// more (that it maybe has in the cache). This avoids that we spoil the
// complete cache with data that we only read once and (due to cache
// size limit) kick out data from the cache that might be still useful
// for the OS or other processes.
// We rollback the initial offset back to the start of the page,
// to avoid it not being truncated as a partial page request.
if (length > 0) {
posix_fadvise(c->fh, offset, length, POSIX_FADV_DONTNEED);
}
// Linux kernels prior to 4.7 have a bug where they truncate
// last partial page of POSIX_FADV_DONTNEED request, so we need
// to page-align it ourselves. We'll need the rest of this page
// on the next read (assuming this was not EOF)
overshoot = (offset + length) & pagemask;
} else {
// For length == 0 we set overshoot 0, so the below
// length - overshoot is 0, which means till end of file for
// fadvise. This will cancel the final page and is not part
// of the above workaround.
overshoot = 0;
}
posix_fadvise(c->fh, offset & ~pagemask, length - overshoot, POSIX_FADV_DONTNEED);
#endif
}
else {