On Tue, 2024-10-15 at 09:12 +0100, Tvrtko Ursulin wrote: > > On 15/10/2024 08:11, Philipp Stanner wrote: > > On Mon, 2024-10-14 at 13:07 +0100, Tvrtko Ursulin wrote: > > > > > > On 14/10/2024 12:32, Philipp Stanner wrote: > > > > Hi, > > > > > > > > On Mon, 2024-10-14 at 11:46 +0100, Tvrtko Ursulin wrote: > > > > > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx> > > > > > > > > > > In FIFO mode We can avoid dropping the lock only to > > > > > immediately > > > > > re- > > > > > acquire > > > > > by adding a new drm_sched_rq_update_fifo_locked() helper. > > > > > > > > > > > > > Please write detailed commit messages, as described here [1]. > > > > 1. Describe the problem: current state and why it's bad. > > > > 2. Then, describe in imperative (present tense) form what > > > > the > > > > commit > > > > does about the problem. > > > > > > Both pieces of info are already there: > > > > > > 1. Drops the lock to immediately re-acquire it. > > > 2. We avoid that by by adding a locked helper. > > > > Optionally, in between can be information about why it's solved > > > > this > > > > way and not another etc. > > > > > > > > Applies to the other patches, too. > > > > > > > > > > > > [1] > > > > https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes > > > > > > Thanks I am new here and did not know this. > > > > > > Seriosuly, lets not be too blindly strict about this because it > > > can > > > get > > > IMO ridiculous. > > > > > > One example when I previously accomodated your request is patch > > > 3/5 > > > from > > > this series: > > > > > > """ > > > Current kerneldoc for struct drm_sched_rq incompletely documents > > > what > > > fields are protected by the lock. > > > > > > This is not good because it is misleading. > > > > > > Lets fix it by listing all the elements which are protected by > > > the > > > lock. > > > """ > > > > > > While this was the original commit text you weren't happy with: > > > > > > """ > > > drm/sched: Re-order struct drm_sched_rq members for clarity > > > > > > Lets re-order the members to make it clear which are protected by > > > the > > > lock > > > and at the same time document it via kerneldoc. > > > """ > > > > > > I maintain the original text was passable. > > > > > > On top, this was just a respin to accomodate the merge process. > > > All > > > approvals were done and dusted couple weeks or so ago so asking > > > for > > > yet > > > another respin for such trivial objections is not great. > > > > I understand that you're unhappy, but please understand the > > position > > I'm coming from. As you know, since you sent these patches within a > > different series (and, thus, since I reviewed them), I was trusted > > with > > co-maintaining this piece of shared infrastructure. > > > > And since you've worked on it a bit now, I suppose you also know > > that > > the GPU Scheduler is arguably in quite a bad shape, has far too > > little > > documentation, has leaks, maybe race conditions, parts *where the > > locking rules are unclear* and is probably only fully understood by > > a > > small hand full of people. I also argue that this is a *very* > > complicated piece of software. > > We already went over that and agreed. Not least I agreed the base is > shaky since few years ago. :) > > Btw if things align, I hope you will at some point see a follow up > series from me which makes some significant simplifications and > improvements at the same time. Cool, good to hear! (Would be even cooler if simplifications and improvements can be delivered through separate patch series to be easier to review etc.) > > So I might be or appear to be a bit pedantic, but I'm not doing > > that to > > terrorize you, but because I want this thing to become well > > documented, > > understandable, and bisectable. Working towards a canonical, idiot- > > proof commit style is one measure that will help with that. > > > > I want to offer you the following: I can be more relaxed with > > things > > universally recognized as trivial (comment changes, struct member > > reordering) – but when something like a lock is touched in any way, > > we > > shall document that in the commit message as canonically as > > possible, > > so someone who's less experienced and just bisected the commit > > immediately understands what has been done (or rather: was supposed > > to > > be done). > > So how would you suggest to expand this commit text so it doesn't > read > too self-repeating? My issue with this particular commit message is mainly that it doesn't make it obvious what the patch is supposed to do. So one can make it quicker and better to review by detailing it a bit more, so the reviewer then can compare commit message vs. what the code does. It seems to me for example that the actual optimization is being done in drm_sched_entity_push_job(), and drm_sched_entity_pop_job() had to be ported, too, for correctness Another small thing that might be cool is something that makes it a bit more obvious that this is an optimization, not a fix. So I would probably write: "So far, drm_sched_rq_update_fifo() automatically takes drm_sched_entity.rq_lock. For DRM_SCHED_POLICY_FIFO, this is inefficient because that lock is then taken, released and retaken in drm_sched_entity_push_job(). Improve performance by moving the locking out of drm_sched_rq_update_fifo()." Not that much longer but makes it far more obvious what shall be achieved where :] (Let me read through the other patches briefly. Then we should be good with v2 of this series.. or would it be v3 then?) Thanks, P. > > Regards, > > Tvrtko >
