[Qemu-devel] [Bug 1321464] Re: qemu/block/qcow2.c:1942: possible performance problem ?

[Thomas Huth]

Thanks for reporting this, but it looks like the related code has been
removed a while ago (there is no more "pad_buf" in qcow.c or qcow2.c),
so closing this ticket. If you still can reproduce the (same or similar)
problem with the latest version of QEMU, please open a new ticket
instead.

** Changed in: qemu
       Status: New => Won't Fix

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https://bugs.launchpad.net/bugs/1321464

Title:
  qemu/block/qcow2.c:1942: possible performance problem ?

Status in QEMU:
  Won't Fix

Bug description:
  I just ran static analyser cppcheck over today (20140520) qemu source
  code.

  It said many things, including

  [qemu/block/qcow2.c:1942] -> [qemu/block/qcow2.c:1943]: (performance) Buffer 
'pad_buf' is being writ
  ten before its old content has been used.

  Source code is

              memset(pad_buf, 0, s->cluster_size);
              memcpy(pad_buf, buf, nb_sectors * BDRV_SECTOR_SIZE);

  Worth tuning ?

  Similar problem here

  [qemu/block/qcow.c:815] -> [qemu/block/qcow.c:816]: (performance) Buffer 
'pad_buf' is being written 
  before its old content has been used.

  and

  [qemu/hw/i386/acpi-build.c:1265] -> [qemu/hw/i386/acpi-build.c:1267]: 
(performance) Buffer 'dsdt' is
   being written before its old content has been used.

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