On Wed, Apr 25, 2018 at 10:46:15PM +1000, luv-main wrote:
# free -m total used free shared buff/cache available Mem: 7962 2212 498 533 5251 4942 Swap: 10719 1732 8986
The above is from my workstation. It's running KDE, Chrome, KTorrent, and not much else. My understanding of the above is that most RAM is being used for cache and it's quite likely that this achieves the goal of reducing the number of storage accesses.
The problem is that I don't want to reduce the number of storage accesses, I want to improve the performance of interactive tasks. Ktorrent is configured to only upload 60KB/s so a lack of caching of the torrents shouldn't prevent it from uploading at the maximum speed I permit. When large interactive programs like Chrome and Kmail get paged out it causes annoying delays when I want to perform what should be quick tasks like replying to a single message or viewing a single web page.
Any suggestions as to how to optimise for this use case? I already have swap on one of the fastest SSDs I own and don't feel like buying NVMe for this purpose or buying a system with more RAM, so software changes are required.
When replying please feel free to diverge from the topic. I think this is an area where most Linux users know less than they would like so randomly educational replies will be appreciated even if they don't help me with this problem.
Wow. I've never seen output from free like that before. My understanding has always been that you only get paging after cache is exhausted, but maybe I have been mistaken all this time. If you run without swap, does the OOM killer come in? Does top show plausibly large working sets for your apps e.g. such that they wouldn't all fit in RAM together? I used to have probems with Firefox using all of 1 cpu and (sometimes) all of RAM as well, but not since I unpinned dilbert.com. HTH Cheers ... Duncan.