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Subject: Re: svn commit: r271946 - in head/sys: dev/oce dev/vmware/vmxnet3
 dev/xen/netfront kern net netinet ofed/drivers/net/mlx4 sys
To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= <royger@FreeBSD.org>,
 src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
References: <201409220827.s8M8RRHB031526@svn.freebsd.org>
 <55F69093.5050807@FreeBSD.org> <55F6935C.9000000@selasky.org>
 <55F7D783.1080406@FreeBSD.org>
From: Hans Petter Selasky <hps@selasky.org>
Message-ID: <55F7D9F2.3020207@selasky.org>
Date: Tue, 15 Sep 2015 10:42:26 +0200
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On 09/15/15 10:32, Roger Pau Monné wrote:
> El 14/09/15 a les 11.29, Hans Petter Selasky ha escrit:
>> On 09/14/15 11:17, Roger Pau Monné wrote:
>>> El 22/09/14 a les 10.27, Hans Petter Selasky ha escrit:

>> Hi Roger,
>>
>> Looking at the netfront code you should subtract 1 from tsomaxsegcount
>> prior to r287775. The reason might simply be that 2K clusters are used
>> instead of 4K clusters, causing m_defrag() to be called.
>>
>>>          ifp->if_hw_tsomax = 65536 - (ETHER_HDR_LEN +
>>> ETHER_VLAN_ENCAP_LEN);
>>>          ifp->if_hw_tsomaxsegcount = MAX_TX_REQ_FRAGS;
>>>          ifp->if_hw_tsomaxsegsize = PAGE_SIZE;
>>
>> After r287775 can you try these settings:
>>
>> ifp->if_hw_tsomax = 65536;
>> ifp->if_hw_tsomaxsegcount = MAX_TX_REQ_FRAGS;
>> ifp->if_hw_tsomaxsegsize = PAGE_SIZE;
>>
>> And see if the performance is the same like before?
>
> FWIW, just using r287775 seems to solve the problem, even if I leave
> if_hw_tsomax with it's current value.
>

That's expected.

Thank you for testing.

--HPS