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  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:   Wed, 1 May 2019 02:44:37 -0700
From:   Matthew Wilcox <>
To:     Eric Dumazet <>
Subject: Re: [PATCH 0/5] Beginnings of skb_frag -> bio_vec conversion

On Wed, May 01, 2019 at 04:14:41AM -0400, Eric Dumazet wrote:
> On 4/30/19 9:17 PM, Matthew Wilcox wrote:
> > It turns out there's a lot of accessors for the skb_frag, which would
> > make this conversion really easy if some drivers didn't bypass them.
> > This is what I've done so far; my laptop's not really beefy enough to
> > cope with changing skbuff.h too often ;-)
> I guess the missing part here is the "why" all this is done ?
> 32 bit hosts will have bigger skb_shared_info and this impacts sk_rcvbuf and sk_sndbuf limits.
> 17 * 4 are 68 extra bytes per skb.

Right.  The plan is to replace get_user_pages() with get_user_bvec().  If
userspace has physically consecutive pages (and often it will, even when
not using THP), we can reduce the number of elements in the array at the
start.  So each skb_frag_t is larger, but you'll have fewer of them for a
large I/O.  Obviously this particularly benefits THP.

Powered by blists - more mailing lists