On Mon, May 11, 2015 at 10:44 PM, Marc MERLIN <marc@xxxxxxxxxxx> wrote: > On Sun, Sep 14, 2014 at 05:18:36PM -0700, Marc MERLIN wrote: >> On Mon, Sep 08, 2014 at 10:49:01PM +0100, Filipe David Manana wrote: >> > Hi Marc, >> > >> > Does the sum of all reads from the stream file (fd 3) gets anywhere >> > close to the total btrfs receive time? (or even more than 50%) >> > Can you paste somewhere the full output of strace (with -T option)? >> >> Sorry for the lack of answer, I lost the snapshot I used for that mail, >> so it was not possible to do again easily. >> Because my backups were so hopelessly behind, I did a full resync of >> /var, i.e. not a differential send (300GB or so). The copy went at about >> 25GB/h, which wasn't bad at all since was over wifi (took about 14H). > > Sigh, now that I'm resyncing my laptop I just rebuilt after the btrfs > crash, to my server (both running 3.19.5+), full btrfs sends (i.e. not > incremental), are taking ages. > > I'm seeing less than 100GB/day on my home network when my tcp > connections over wifi easily get 50MB/s > > Right now I'm seeing the equivalent of aout 1MB/s, or 50 times less than > what my network connection can do. > > Last time I tried to strace btrfs send, it killed the process with > SIGPIPE and I lost a full day of sync and had to start over :( > > It's a broad question, but how can I diagnose btrfs send being so slow > without taking the risk of killing my connection? > (if there is no good answer on this one, I can try another sync later > with -vvv and strace if you'd like) Try to see if it's a problem at the sending side or at the receiving side. Redirect send's output to a file, see how much it takes. Then run receive with that file as input and see how long it takes. You can also use 'perf record -ag' while doing both, it might give some useful information. > > Thanks, > Marc > -- > "A mouse is a device used to point at the xterm you want to type in" - A.S.R. > Microsoft is to operating systems .... > .... what McDonalds is to gourmet cooking > Home page: http://marc.merlins.org/ | PGP 1024R/763BE901 -- Filipe David Manana, "Reasonable men adapt themselves to the world. Unreasonable men adapt the world to themselves. That's why all progress depends on unreasonable men." -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
