Hello, additional information:
- when the TX ring size is set to 24, we experience no system freeze, but the connectivity is severely impaired: PING 143.225.28.254 (143.225.28.254) 56(84) bytes of data. 64 bytes from 143.225.28.254: icmp_seq=5 ttl=255 time=0.332 ms ^C --- 143.225.28.254 ping statistics --- 18 packets transmitted, 1 received, 94% packet loss, time 17229ms rtt min/avg/max/mdev = 0.332/0.332/0.332/0.000 ms - when the TX ring size is set to 32, the percentage of ping packet loss is 0% (throughput not investigated yet). Any idea how to explain the different behaviors when the TX ring size is set to 16, 24 and 32? Thanks a lot in advance. Bests, Stefano On Wed, Nov 16, 2016 at 11:08 AM, Stefano Avallone <stava...@gmail.com> wrote: > Hello, > > we want to make experiments with smaller TX ring sizes to evaluate how > much the throughput decreases. We are using two distinct NICs on two > different PCs: > > Ethernet controller: Intel Corporation Ethernet Connection (2) I219-LM > (rev 31) > > and > > Ethernet controller: Intel Corporation Ethernet Connection I217-LM (rev > 04) > > both using the e1000e kernel module (kernel 4.8.7, module version 3.2.6) > > We recompiled the e1000e module with the following patch: > > --- linux-4.8/drivers/net/ethernet/intel/e1000e/e1000.h.orig > 2016-11-15 15:42:18.181412740 +0100 > +++ linux-4.8/drivers/net/ethernet/intel/e1000e/e1000.h 2016-11-15 > 15:42:55.961607611 +0100 > @@ -64,7 +64,7 @@ > /* Tx/Rx descriptor defines */ > #define E1000_DEFAULT_TXD 256 > #define E1000_MAX_TXD 4096 > -#define E1000_MIN_TXD 64 > +#define E1000_MIN_TXD 4 > > #define E1000_DEFAULT_RXD 256 > #define E1000_MAX_RXD 4096 > > Then, we set the TX ring size to 16 with ethtool: > > sudo ethtool -G <iface> tx 16 > > The change was applied (as confirmed by ethtool -g) but the whole system > freezed a few seconds later. This happens every time we set the tx ring > size to 16. We cannot ping the machine nor ssh into it, we can only force > shutdown. Looking at the journal log (systemd) there is no sign of the > freeze. > > We would like to know if there are known issues that prevent setting the > TX ring size below a certain threshold. Also, we would appreciate it very > much if someone could advise what to do to investigate/solve the issue we > are facing. > > Thanks a lot in advance for any help. > > Bests, > Stefano > >
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