On 16 February 2018 at 02:48, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Fri, Feb 16, 2018 at 12:02:28AM +0500, Mikhail Gavrilov wrote: >> On 15 February 2018 at 10:44, Dave Chinner <david@xxxxxxxxxxxxx> wrote: >> > I've already explained that we can't annotate these memory >> > allocations to turn off the false positives because that will also >> > turning off all detection of real deadlock conditions. Lockdep has >> > many, many limitations, and this happens to be one of them. >> > >> > FWIW, is there any specific reason you running lockdep on your >> > desktop system? >> >> Because I wanna make open source better (help fixing all freezing) > > lockdep isn't a user tool - most developers don't even understand > what it tries to tell them. Worse, it is likely contributing to your > problems as it has a significant runtime CPU and memory overhead.... I don't know how else collect debug info about freezes which occurring accidentally. Is there a better idea? >> > I think I've already explained that, too. The graphics subsystem - >> > which is responsible for updating the cursor - requires memory >> > allocation. The machine is running low on memory, so it runs memory >> > reclaim, which recurses back into the filesystem and blocks waiting >> > for IO to be completed (either writing dirty data pages or flushing >> > dirty metadata) so it can free memory. >> >> Which means machine is running low on memory? >> How many memory needed? >> >> $ free -h >> total used free shared buff/cache available >> Mem: 30G 17G 2,1G 1,4G 10G 12G >> Swap: 59G 0B 59G >> >> As can we see machine have 12G available memory. Is this means low memory? > > No, you only have 2.1G free memory. You have 10GB of *reclaimable > memory* in the buffer/page cache, and that gives you 12GB of > "available memory". Memory reclaim happens all the time in a normal > system - it does not mean you are running low on memory, it just > means your system is busy. > > And, FWIW, we know you have memory pressure because the lockdep > reports you are pasting are a result of memory reclaim operating. > Anyway I believe that memory pressure should not lead to such lockdep reports. Looks like something wrong but not on file system side, may be on side memory management. Last 24 hours I don't see lockdep reports, but short-term interface freezing whatever occurs. >> > IOWs, your problems all stem from long IO latencies caused by the >> > overloaded storage subsystem - they are propagate to all >> > aspects of the OS via direct memory reclaim blocking on IO.... >> >> I'm surprised that no QOS analog for disk I/O. > > There is, but it's not like a network where overload situations are > mitigated by dropping packets to reduce load. We cannot do that with > IO (dropped IO == broken filesystem), so QoS doesn't help when you > drive the storage subsystem in extreme, long term overload > conditions as you seem to be doing. I no suggest broke file system I suggest reserving I/O and memory for proceses who need realtime work for example for GUI (gnome-shell). I this way high I/O and memory pressure couldn't affect to user experience. > >> This is reminiscent of the situation in past where a torrent client >> clogs the entire channel on the cheap router and it causes problems >> with opening web pages. In nowadays it never happens with modern >> routers even with overloaded network channel are possible video calls > > Storage != network. > >> In 2018 my personaly expectation that user can run any set of >> applications on computer and this never shoudn't harm system. > > There's no "harm" occurring on your system - it's just slow > because the load you've put on it means no task can execute quickly. slow != freeze I have nothing against long time launching and long time working applications, but system freezing hurts everybody. -- Best Regards, Mike Gavrilov. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
