Oct 26, 2013 02:44:07 AM, neil wrote: On Fri, 25 Oct 2013 18:26:23 +0000 (UTC) "Artem S. Tashkinov" >> >> Exactly. And not being able to use applications which show you IO performance >> like Midnight Commander. You might prefer to use "cp -a" but I cannot imagine >> my life without being able to see the progress of a copying operation. With the current >> dirty cache there's no way to understand how you storage media actually behaves. > >So fix Midnight Commander. If you want the copy to be actually finished when >it says it is finished, then it needs to call 'fsync()' at the end. This sounds like a very bad joke. How applications are supposed to show and calculate an _average_ write speed if there are no kernel calls/ioctls to actually make the kernel flush dirty buffers _during_ copying? Actually it's a good way to solve this problem in user space - alas, even if such calls are implemented, user space will start using them only in 2018 if not further from that. >> >> Per device dirty cache seems like a nice idea, I, for one, would like to disable it >> altogether or make it an absolute minimum for things like USB flash drives - because >> I don't care about multithreaded performance or delayed allocation on such devices - >> I'm interested in my data reaching my USB stick ASAP - because it's how most people >> use them. >> > >As has already been said, you can substantially disable the cache by tuning >down various values in /proc/sys/vm/. >Have you tried? I don't understand who you are replying to. I asked about per device settings, you are again referring me to system wide settings - they don't look that good if we're talking about a 3MB/sec flash drive and 500MB/sec SSD drive. Besides it makes no sense to allocate 20% of physical RAM for things which don't belong to it in the first place. I don't know any other OS which has a similar behaviour. And like people (including me) have already mentioned, such a huge dirty cache can stall their PCs/servers for a considerable amount of time. Of course, if you don't use Linux on the desktop you don't really care - well, I do. Also not everyone in this world has an UPS - which means such a huge buffer can lead to a serious data loss in case of a power blackout. Regards, Artem -- 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>