linux-kernel - Re: Implementing NVMHCI...

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]

Date:	Sat, 11 Apr 2009 19:51:31 -0400
From:	Jeff Garzik <jeff@...zik.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Grant Grundler <grundler@...gle.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux IDE mailing list <linux-ide@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Jens Axboe <jens.axboe@...cle.com>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: Implementing NVMHCI...

Alan Cox wrote:
>> We've abstract the DMA mapping/SG list handling enough that the
>> block size should make no more difference than it does for the
>> MTU size of a network.
> 
> You need to start managing groups of pages in the vm and keeping them
> together and writing them out together and paging them together even if
> one of them is dirty and the other isn't. You have to deal with cases
> where a process forks and the two pages are dirtied one in each but still
> have to be written together.
> 
> Alternatively you go for read-modify-write (nasty performance hit
> especially for RAID or a log structured fs).

Or just ignore the extra length, thereby excising the 'read-modify' 
step...  Total storage is halved or worse, but you don't take as much of 
a performance hit.

	Jeff



--
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/