Subject: Re: REGRESSION f54b311142a92ea2e42598e347b84e1655caf8e3 tcp auto corking slows down iSCSI file system creation by factor of 70 [WAS: 4 TB VMFS creation takes 15 minutes vs 26 seconds]

From: Thomas Glanzmann <[email-masked]>
Date: Sat, 8 Feb 2014 14:38:47 +0100

Hello Eric,

> Also make sure you have commit a181ceb501b31b4bf8812a5c84c716cc31d82c2d
> ("tcp: autocork should not hold first packet in write queue")
> in your tree.

confirmed:

(node-62) [~/work/linux-2.6] git show a181ceb501b31b4bf8812a5c84c716cc31d82c2d | head
commit a181ceb501b31b4bf8812a5c84c716cc31d82c2d
Author: Eric Dumazet <[email-masked]>
Date:   Tue Dec 17 09:58:30 2013 -0800

    tcp: autocork should not hold first packet in write queue

    Willem noticed a TCP_RR regression caused by TCP autocorking
    on a Mellanox test bed. MLX4_EN_TX_COAL_TIME is 16 us, which can be
    right above RTT between hosts.

Cheers,
        Thomas