On Fri, Aug 18, 2017 at 02:18:53PM +0100, Stefan Hajnoczi wrote: > On Fri, Aug 18, 2017 at 03:39:20PM +1000, Alexey Kardashevskiy wrote: > > ==94451== -------------------- 4 of 10 -------------------- > > ==94451== max-live: 314,649,600 in 150 blocks > > ==94451== tot-alloc: 314,649,600 in 150 blocks (avg size 2097664.00) > > ==94451== deaths: none (none of these blocks were freed) > > ==94451== acc-ratios: 0.00 rd, 0.00 wr (0 b-read, 0 b-written) > > ==94451== at 0x4895600: memalign (in > > /usr/lib/valgrind/vgpreload_exp-dhat-ppc64le-linux.so) > > ==94451== by 0x48957E7: posix_memalign (in > > /usr/lib/valgrind/vgpreload_exp-dhat-ppc64le-linux.so) > > ==94451== by 0xB744AB: qemu_try_memalign (oslib-posix.c:106) > > ==94451== by 0xA92053: qemu_try_blockalign (io.c:2493) > > ==94451== by 0xA34DDF: qcow2_do_open (qcow2.c:1365) > > ==94451== by 0xA35627: qcow2_open (qcow2.c:1526) > > ==94451== by 0x9FB94F: bdrv_open_driver (block.c:1109) > > ==94451== by 0x9FC413: bdrv_open_common (block.c:1365) > > ==94451== by 0x9FF823: bdrv_open_inherit (block.c:2542) > > ==94451== by 0x9FFC17: bdrv_open (block.c:2626) > > ==94451== by 0xA71027: blk_new_open (block-backend.c:267) > > ==94451== by 0x6D3E6B: blockdev_init (blockdev.c:588) > > This allocation is unnecessary. Most qcow2 files are not encrypted so > s->cluster_data does not need to be allocated upfront. > > I'll send a patch.
Is that sufficient to explain the problem, I can't quickly see how big
that unnecessary allocation is - but would it account for the 10s of
gigabytes usage we're seeing here?
I'm suspecting we accidentally have a O(n^2) or worse space complexity
going on here.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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