Commit Graph

16 Commits

Author SHA1 Message Date
Max Reitz 6725f887ac hbitmap: Fix shifts of constants by granularity
An hbitmap's granularity may be anything from 0 to 63, so when shifting
constants by its value, they should not be plain ints.

Even having changed the types, hbitmap_serialization_granularity() still
tries to shift 64 to the right by the granularity. This operation is
undefined if the granularity is greater than 57. Adding an assertion is
fine for now, because serializing is done only in tests so far, but this
means that only bitmaps with a granularity below 58 can be serialized
and we should thus add a hbitmap_is_serializable() function later.

One of the two places touched in this patch uses
QEMU_ALIGN_UP(x, 1 << y). We can use ROUND_UP() there, since the second
parameter is obviously a power of two.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20161115224732.1334-1-mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2016-11-29 17:46:36 +08:00
Vladimir Sementsov-Ogievskiy 8258888e22 hbitmap: serialization
Functions to serialize / deserialize(restore) HBitmap. HBitmap should be
saved to linear sequence of bits independently of endianness and bitmap
array element (unsigned long) size. Therefore Little Endian is chosen.

These functions are appropriate for dirty bitmap migration, restoring
the bitmap in several steps is available. To save performance, every
step writes only the last level of the bitmap. All other levels are
restored by hbitmap_deserialize_finish() as a last step of restoring.
So, HBitmap is inconsistent while restoring.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[Fix left shift operand to 1UL; add "finish" parameter. - Fam]
Signed-off-by: Fam Zheng <famz@redhat.com>

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1476395910-8697-8-git-send-email-jsnow@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-10-24 17:56:07 +02:00
Fam Zheng 07ac4cdb57 HBitmap: Introduce "meta" bitmap to track bit changes
Upon each bit toggle, the corresponding bit in the meta bitmap will be
set.

Signed-off-by: Fam Zheng <famz@redhat.com>
[Amended text inline. --js]
Reviewed-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1476395910-8697-3-git-send-email-jsnow@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-10-24 17:56:07 +02:00
Vladimir Sementsov-Ogievskiy 0e32119122 hbitmap: add 'pos < size' asserts
For now, fail in hbitmap_set on start + count > size will come from
hbitmap_set
  hb_count_between
    hbitmap_iter_init
      assert(pos < hb->size)

This patch adds such checks to set/get/reset functions of hbitmap.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 1465924093-76875-2-git-send-email-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-06-16 15:20:37 +02:00
Peter Maydell 030c98aff1 all: Remove unnecessary glib.h includes
Remove glib.h includes, as it is provided by osdep.h.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2016-06-07 18:19:24 +03:00
Peter Maydell aafd758410 util: Clean up includes
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1454089805-5470-6-git-send-email-peter.maydell@linaro.org
2016-02-04 17:01:04 +00:00
Wen Congyang c6a8c3283f util/hbitmap: Add an API to reset all set bits in hbitmap
The function bdrv_clear_dirty_bitmap() is updated to use
faster hbitmap_reset_all() call.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 555E868A.60506@cn.fujitsu.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2015-06-23 15:06:16 +01:00
John Snow ce1ffea8cd block: Resize bitmaps on bdrv_truncate
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-16-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-04-28 15:36:10 +02:00
John Snow be58721dbf hbitmap: add hbitmap_merge
We add a bitmap merge operation to assist in error cases
where we wish to combine two bitmaps together.

This is algorithmically O(bits) provided HBITMAP_LEVELS remains
constant. For a full bitmap on a 64bit machine:
sum(bits/64^k, k, 0, HBITMAP_LEVELS) ~= 1.01587 * bits

We may be able to improve running speed for particularly sparse
bitmaps by using iterators, but the running time for dense maps
will be worse.

We present the simpler solution first, and we can refine it later
if needed.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-8-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-04-28 15:36:10 +02:00
John Snow 8515efbef1 hbitmap: cache array lengths
As a convenience: between incremental backups, bitmap migrations
and bitmap persistence we seem to need to recalculate these a lot.

Because the lengths are a little bit-twiddly, let's just solidly
cache them and be done with it.

Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-7-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-04-28 15:36:10 +02:00
Markus Armbruster e1cf558264 util: Use g_new() & friends where that makes obvious sense
g_new(T, n) is neater than g_malloc(sizeof(T) * n).  It's also safer,
for two reasons.  One, it catches multiplication overflowing size_t.
Two, it returns T * rather than void *, which lets the compiler catch
more type errors.

This commit only touches allocations with size arguments of the form
sizeof(T).

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2014-12-10 11:34:15 +03:00
Peter Maydell 591b320ad0 util/hbitmap.c: Use ctpopl rather than reimplementing a local equivalent
The function popcountl() in hbitmap.c is effectively a reimplementation
of what host-utils.h provides as ctpopl(). Use ctpopl() directly; this fixes
a failure to compile on NetBSD (whose strings.h erroneously exposes a
system popcountl() which clashes with this one).

Reported-by: Martin Husemann <martin@duskware.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-06-11 00:25:06 +01:00
Richard Henderson 18331e7c18 hbitmap: Use non-bitops ctzl
Both uses of ctz have already eliminated zero, and thus the difference
in edge conditions between the two routines is irrelevant.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2013-02-16 11:11:34 +00:00
Paolo Bonzini fbeadf50f2 bitops: unify bitops_ffsl with the one in host-utils.h, call it bitops_ctzl
We had two copies of a ffs function for longs with subtly different
semantics and, for the one in bitops.h, a confusing name: the result
was off-by-one compared to the library function ffsl.

Unify the functions into one, and solve the name problem by calling
the 0-based functions "bitops_ctzl" and "bitops_ctol" respectively.

This also fixes the build on platforms with ffsl, including Mac OS X
and Windows.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Andreas Färber <afaerber@suse.de>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2013-02-02 20:16:00 +00:00
Paolo Bonzini 1b09524455 hbitmap: add assertion on hbitmap_iter_init
hbitmap_iter_init causes an out-of-bounds access when the "first"
argument is or greater than or equal to the size of the bitmap.
Forbid this with an assertion, and remove the failing testcase.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-01-25 18:18:35 +01:00
Paolo Bonzini e7c033c3fa add hierarchical bitmap data type and test cases
HBitmaps provides an array of bits.  The bits are stored as usual in an
array of unsigned longs, but HBitmap is also optimized to provide fast
iteration over set bits; going from one bit to the next is O(logB n)
worst case, with B = sizeof(long) * CHAR_BIT: the result is low enough
that the number of levels is in fact fixed.

In order to do this, it stacks multiple bitmaps with progressively coarser
granularity; in all levels except the last, bit N is set iff the N-th
unsigned long is nonzero in the immediately next level.  When iteration
completes on the last level it can examine the 2nd-last level to quickly
skip entire words, and even do so recursively to skip blocks of 64 words or
powers thereof (32 on 32-bit machines).

Given an index in the bitmap, it can be split in group of bits like
this (for the 64-bit case):

     bits 0-57 => word in the last bitmap     | bits 58-63 => bit in the word
     bits 0-51 => word in the 2nd-last bitmap | bits 52-57 => bit in the word
     bits 0-45 => word in the 3rd-last bitmap | bits 46-51 => bit in the word

So it is easy to move up simply by shifting the index right by
log2(BITS_PER_LONG) bits.  To move down, you shift the index left
similarly, and add the word index within the group.  Iteration uses
ffs (find first set bit) to find the next word to examine; this
operation can be done in constant time in most current architectures.

Setting or clearing a range of m bits on all levels, the work to perform
is O(m + m/W + m/W^2 + ...), which is O(m) like on a regular bitmap.

When iterating on a bitmap, each bit (on any level) is only visited
once.  Hence, The total cost of visiting a bitmap with m bits in it is
the number of bits that are set in all bitmaps.  Unless the bitmap is
extremely sparse, this is also O(m + m/W + m/W^2 + ...), so the amortized
cost of advancing from one bit to the next is usually constant.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-01-25 18:18:32 +01:00