On Wed, Aug 19, 2020 at 01:45:37PM +0200, Michal Privoznik wrote: > On 8/18/20 10:48 AM, Erik Skultety wrote: > > On Mon, Aug 17, 2020 at 10:37:18AM +0530, Prathamesh Chavan wrote: > > > Reference to `maxQueuedJobs` required us to access > > > config of the qemu-driver. And creating its copy in > > > the `qemuDomainJob` helped us access the variable > > > without referencing the driver's config. > > > > > > Signed-off-by: Prathamesh Chavan <pc44800@xxxxxxxxx> > > > --- > > > src/qemu/qemu_domain.c | 5 ++++- > > > src/qemu/qemu_domainjob.c | 13 +++++++------ > > > src/qemu/qemu_domainjob.h | 4 +++- > > > 3 files changed, 14 insertions(+), 8 deletions(-) > > > > > > > Looking at this again, I don't think we want to move any of the jobs_queued or > > maxQueuedJobs attributes to the job structure, I'm sorry I didn't spot this > > right away in the previous revision of the series, I take responsibility for > > it. > > The job structure represents a single job, so from the design POV, > > referencing both jobs_queued (which is really tied to a domain) and > > maxQueuedJobs (which is a global driver setting) from within the job structure > > simply doesn't feel right. Instead, I think qemuDomainObjBeginJobInternal will > > simply have to be split in parts specific to QEMU that have access to the > > driver and hypervisor-agnostic bits that can be moved to src/hypervisor. > > Actually, I think maxQueuedJobs is job specific and not a global driver > setting. I mean, I can imagine other drivers benefiting from it too. > It's true that we currently don't allow specifying different values for > different domains and only apply the setting from qemu.conf, but in the > future we might make this available in domain XML somehow [1] and thus be > per domain. Moreover, I can imagine users wanting to set the limit for > volumes too [2]. I can relate to the reasoning, but I still don't think the Job structure is the right place, like I said, it holds everything that a single job needs, from that POV a single job doesn't really need to do anything with that value, it's just it happens to be a very convenient place right now, I say let's try finding a different location for the attribute where it makes more sense. Erik > > Michal > > 1: this refers to discussion we had on the list (too lazy to find the link, > sorry) about the qemu:///embed. So far, if an user wants to set some values, > they have to create qemu.conf in the root before connecting to the embed > driver (so that the driver loads them). The idea was to allow them to > specify everything in domain XML so no file needs to be created. > > 2: although, it's not as bad as it used to be, but with rotational disks > having two processes accessing different portions of a file resulted in very > poor performance as the head had to jump up & down.
