From: Jens Axboe <jaxboe@fusionio.com>
To: Matthew Wilcox <matthew@wil.cx>
Cc: Luben Tuikov <ltuikov@yahoo.com>, Greg KH <greg@kroah.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"tj@kernel.org" <tj@kernel.org>,
James Bottomley <James.Bottomley@HansenPartnership.com>
Subject: Re: SCSI TMF processing; tag allocation
Date: Mon, 15 Nov 2010 10:28:04 +0100 [thread overview]
Message-ID: <4CE0FD24.4030000@fusionio.com> (raw)
In-Reply-To: <20101113123750.GF18258@parisc-linux.org>
>> Third, and most importantly, tags should form an increasing sequence and should not be reused until all other tags after it and before it have been reused. This for example can be accomplished if one were to use
>> find_next_zero_bit() with non-zero "offset", it being the last allocated
>> tag in a modulo the number of tags manner. That is, find_next_zero_bit()
>> could wrap as well as starting from an offset or the caller could implement
>> that via two calls to this function, in blk_queue_start_tag().
Care to explain your reasoning? For starvation issues? At least I'm not
aware of any correctness issues in that regard, but doing tag cycling in
this fashion seems like a good idea just to prevent starvation alone by
an ill behaving device.
--
Jens Axboe
next prev parent reply other threads:[~2010-11-15 9:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-06 6:02 SCSI TMF processing; tag allocation Luben Tuikov
2010-11-13 12:37 ` Matthew Wilcox
2010-11-15 9:28 ` Jens Axboe [this message]
2010-11-15 14:33 ` James Bottomley
2010-11-15 14:40 ` Alan Cox
2010-11-15 14:53 ` James Bottomley
2010-11-15 14:46 ` Matthew Wilcox
2010-11-15 14:52 ` James Bottomley
2010-11-16 20:28 ` Vladislav Bolkhovitin
2010-11-15 18:53 ` Douglas Gilbert
2010-11-15 19:09 ` Matthew Wilcox
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