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Message-ID: <52D28238.5010903@dev.mellanox.co.il>
Date: Sun, 12 Jan 2014 13:53:28 +0200
From: Sagi Grimberg <sagig@dev.mellanox.co.il>
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To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>,
        Sagi Grimberg <sagig@mellanox.com>
CC: "Nicholas A. Bellinger" <nab@daterainc.com>,
        target-devel <target-devel@vger.kernel.org>,
        linux-scsi <linux-scsi@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Christoph Hellwig <hch@lst.de>, Hannes Reinecke <hare@suse.de>,
        Or Gerlitz <ogerlitz@mellanox.com>
Subject: Re: [PATCH 13/14] target/rd: Add DIF protection into rd_execute_rw
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<SNIP>

>> I wander how we can skip  sbc_dif_verify_xxxx if the transport already
>> offloaded DIF verify.
>> I think that the transport should signal the core layer that it is able
>> to offload DIF (ADD/STRIP/PASS/VERIFY), in which case the core should
>> turn off the backstore DIF verify emulation to sustain performance.
> So IBLOCK + PSCSI backends will need to be a non interleaved protection
> PASS for fast path operation, and backend protection emulation is
> reserved for RAMDISK and perhaps a special FILEIO full emulation mode.

But can't we avoid that if transport already verified? This will kill 
performance.

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