On Mon, 2018-04-30 at 18:01 -0400, Jape Person wrote: > Two recent kernel upgrades seem to have both affected the Intel > Corporation Wireless 7265 (rev 59) adapters on our systems in a > manner which causes their network transfer rates to be reduced > dramatically. File transfers which normally require a few > minutes are now taking several hours. > > These systems are running the Debian testing distribution with > the iwilwifi drivers from Debian's testing/contrib. The altered > behavior came when the Debian linux-image version advanced to > 4.15.*. > > I looked online for similar reports and didn't find anything > that seemed directly applicably. I finally got lucky when I > experimented with the net.ipv4.tcp_congestion_control setting. > > I understand that in version 4.15 of the kernel the default was > changed from cubic to bbr. I used > > # sysctl net.ipv4.tcp_congestion_control=cubic > > to revert to the previous default on all of the systems. This > has caused all of the systems to return to their normal file > transfer speeds. > > Please let me know by direct reply (I'm not subscribed.) if I > can supply more information. Do you see anything in dmesg? SYSASSERT messages or something? Please send your dmesg so we can take a look. Are you by any chance using NFS? Emmanuel has recently fixed a problem that was occurring with NFS (but probably happens with other protocols too). Can you apply the patch included in the following bugzilla report and see if it helps? https://bugzilla.kernel.org/show_bug.cgi?id=199209#c18 -- Cheers, Luca.
