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From: Sagi Grimberg <sagi@grimberg.me>
To: Max Gurtovoy <maxg@mellanox.com>,
	Jason Gunthorpe <jgg@mellanox.com>,
	Sergey Gorenko <sergeygo@mellanox.com>
Cc: "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
Subject: Re: [PATCH v1] IB/iser: Support up to 16MB data transfer in a single command
Date: Thu, 12 Sep 2019 14:45:41 -0700
Message-ID: <31f80a22-04dc-d144-7bac-940eb8f2b97d@grimberg.me> (raw)
In-Reply-To: <b49453d9-d419-f804-35a9-757a9b8206b9@mellanox.com>


>>> Maximum supported IO size is 8MB for the iSER driver. The
>>> current value is limited by the ISCSI_ISER_MAX_SG_TABLESIZE
>>> macro. But the driver is able to handle 16MB IOs without any
>>> significant changes. Increasing this limit can be useful for
>>> the storage arrays which are fine tuned for IOs larger than
>>> 8 MB.
>>>
>>> This commit allows to configure maximum IO size up to 16MB
>>> using the max_sectors module parameter.
>>>
>>> Signed-off-by: Sergey Gorenko <sergeygo@mellanox.com>
>>> Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
>>> Acked-by: Sagi Grimberg <sagi@grimberg.me>
>>> ---
>>> Changes from v0:
>>> - Change 512 to SECTOR_SIZE (suggested by Sagi)
> 
> is this always true ? 512 == SECTOR_SIZE ?

 From the documentation it is, and nothing suggest otherwise.
/*
  * The basic unit of block I/O is a sector. It is used in a number of 
contexts
  * in Linux (blk, bio, genhd). The size of one sector is 512 = 2**9
  * bytes. Variables of type sector_t represent an offset or size that is a
  * multiple of 512 bytes. Hence these two constants.
  */
#ifndef SECTOR_SHIFT
#define SECTOR_SHIFT 9
#endif
#ifndef SECTOR_SIZE
#define SECTOR_SIZE (1 << SECTOR_SHIFT)
#endif

      reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-12 10:35 Sergey Gorenko
2019-09-12 15:19 ` Jason Gunthorpe
2019-09-12 21:14   ` Max Gurtovoy
2019-09-12 21:45     ` Sagi Grimberg [this message]

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