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restore: Restore as many pages at once as possible

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When the VMA being restored is not COW-ed we read pages from images
one-by-one which results in suboptimal pages.img access. Fix this
by reading as many pages from iamge at once as possible withing the
active pagemap and VMA.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Pavel Emelyanov 2015-11-09 15:46:58 +03:00
parent 780d699401
commit 03b217c0a6
1 changed files with 24 additions and 4 deletions
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28
cr-restore.c
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@ -468,8 +468,8 @@ static int restore_priv_vma_content(void)
ret = pr.read_pages(&pr, va, 1, buf);
if (ret < 0)
goto err_read;
va += PAGE_SIZE;
va += PAGE_SIZE;
nr_compared++;
if (memcmp(p, buf, PAGE_SIZE) == 0) {
@ -477,15 +477,35 @@ static int restore_priv_vma_content(void)
continue;
}
nr_restored++;
memcpy(p, buf, PAGE_SIZE);
} else {
ret = pr.read_pages(&pr, va, 1, p);
int nr, j;
/*
* Try to read as many pages as possible at once.
*
* Within the current pagemap we still have
* nr_pages - i pages (not all, as we might have
* switched VMA above), within the current VMA
* we have at most (vma->end - current_addr) bytes.
*/
nr = min(nr_pages - i, (vma->e->end - va) / PAGE_SIZE);
ret = pr.read_pages(&pr, va, nr, p);
if (ret < 0)
goto err_read;
va += PAGE_SIZE;
va += nr * PAGE_SIZE;
nr_restored += nr;
i += nr - 1;
/* FIXME -- optimize */
for (j = 1; j < nr; j++)
set_bit(off + j, vma->page_bitmap);
}
nr_restored++;
}
if (pr.put_pagemap)