[pve-devel] Default cache mode for VM hard drives

[Stanislav German-Evtushenko]

On Thu, May 28, 2015 at 6:35 PM, Dietmar Maurer <dietmar at proxmox.com> wrote:
>> This is not okay and this is what is actually happening:
>> 0. set_buffer
>> 1. start_writing_with_o_direct_from_buffer
>> 2. change_buffer (we can do this only in another thread)
>> 3. finish_writing_with_o_direct_from_buffer
>> 4. change_buffer
>> 5. start_writing_with_o_direct_from_buffer
>> 6. change_buffer (we can do this only in another thread)
>> 7. finish_writing_with_o_direct_from_buffer
>> 8 ...
>
> But there is currently only one io-thread in qemu, so this
> cannot happen with qemu if above is the only problem?

But there are other threads, right? Buffer can be changed by another
thread where guest OS itself is running.