Hi, While there are lots of e-mails on this thread, I decided to reply to this one.
I use locate several times per day on every linux computer I use, and I often manually update the database, including after a new machine startup (VM, for example). I consider it to be one of the most useful commands available. But yes, could install the package myself if I have to. However, I will forgot this discussion and go through the "Oh ya, I have to Install it now" moment that someone mentioned. On 2019.05.24 12:02 Steve Langasek wrote: > On Thu, May 23, 2019 at 03:13:49PM -0400, Little Girl wrote: > Steve Langasek wrote: >> I don't think the benefit of having locate available by default >> justifies the daily disk thrashing / energy usage on every Ubuntu >> machine everywhere. >> Just curious, but how bad (or excessive or whatever) is this disk >> thrashing / energy usage that you mentioned? > It is difficult to answer this in aggregate because the data is hard to come > by, and it definitely varies by type of disk and by number of files on the > system. You can get a sense of the effect on your own system by running > e.g. 'sudo iostat /dev/sda 30' in one window and 'sudo > /etc/cron.daily/mlocate' in another. On my otherwise-idle desktop with an > SSD, that only takes 3 seconds to complete and it only reads a few hundred > MB of data off the disk (in order to open every directory and stat every > file). > > I only have about 1.5 million files on my disk. > > On machines with a lot more files; or machines with spinning disks instead > of SSDs; or heavily loaded servers, the impact is bound to be much higher > that 3 seconds of I/O. The "daily disk thrashing" is a very strong function of memory caching. Example 1: My main gateway/router/firewall Ubuntu server, with magnetic disk: Number of files: ~ 0.80 million. Time to update database starting from flushed memory: 10.7 seconds Time to update database starting from approximately fully cached directory stuff: 0.5 seconds. Actual time for the cron daily mlocate task to run last night: 1 second. Locate time (entire disk): 1.1 seconds Find time (entire disk): 26.7 seconds Example 2: My main Ubuntu test server, with magnetic disk: Number of files: 4.3 million and 6.3 million, after adding 2 million for testing. Time to update locate database starting from flushed memory: After adding 2 million files: 12 minutes 45 seconds. With no/minimal file changes: 10 minutes 50 seconds. With no/minimal file changes and lots of cached directory stuff: 4.2 seconds. Time to update database starting from lots of cached directory stuff: After adding 2 million files: fast (did not write it down) With no/minimal file changes: 4.2 seconds. Actual time for the cron daily mlocate task to run last night: 6 seconds. Locate time (entire disk): 2.7 seconds Find time (entire disk, memory flushed): 17 minutes 42 seconds Find time (entire disk, lots of cached directory stuff): 14.2 seconds. For "energy usage": I think it is minimal and well worth it. My main test server processor seems to take about 1 extra watt while the locate database update task is running. (I do have a good mains power data logger, but didn't hook it up for this.) So, for last nights 6 second run time that is 6 Joules of extra processor power. Guess at 3 times that power back at the mains for 18 Joules. (even with no caching it's < 2000 Joules for the 11 minutes.) ... Doug -- ubuntu-devel mailing list ubuntu-devel@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel
