linux-kernel - Re: [dm-devel] [PATCH] staging: writeboost: Add dm-writeboost

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <54885C22.3030808@gmail.com>
Date:	Wed, 10 Dec 2014 23:43:46 +0900
From:	Akira Hayakawa <ruby.wktk@...il.com>
To:	ejt@...hat.com
CC:	dm-devel@...hat.com, gregkh@...uxfoundation.org,
	snitzer@...hat.com, agk@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [dm-devel] [PATCH] staging: writeboost: Add dm-writeboost

On 12/10/14 10:42 PM, Joe Thornber wrote:
> On Wed, Dec 10, 2014 at 10:31:31PM +0900, Akira Hayakawa wrote:
>> Joe,
>>
>>> So you copy the bio payload to a different block of ram and then
>>> complete the bio?  Or does the rambuf refer to the bio payload
>>> directly?
>> Good question.
>> The answer is, copy the data (got by bio_data(bio)) to rambuf once
>> and ack if it's not barrier things.
>> It would be nice if data in rambuf points to bio payload but it now copies
>> because bio payload can be reused after completion. Am I right?
>> Is there a way of eliminate memory copying?
> 
> You *have* to eliminate this memory copying.  Remap the bios to the
> relevant portion of your log, and don't complete them until you log
> chunk is coherent.
> 

Barrier writes don't ack until the log is written on cache device.
I guess treating other writes as well will do this work.

But, it will be much better if I can do this by manipulating reference count
of the bio payload. I am not sure how the implementation would be.

Anyway, thanks for advice,

- Akira
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/