linux-kernel - Re: [PATCH 07/15] mm: Add ___GFP

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:	Mon, 02 Mar 2015 16:04:05 -0600
From:	Tom Zanussi <tom.zanussi@...ux.intel.com>
To:	Alexei Starovoitov <ast@...mgrid.com>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Andi Kleen <andi@...stfloor.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 07/15] mm: Add ___GFP_NOTRACE

On Mon, 2015-03-02 at 11:29 -0800, Alexei Starovoitov wrote:
> On Mon, Mar 2, 2015 at 10:54 AM, Tom Zanussi
> <tom.zanussi@...ux.intel.com> wrote:
> >> >
> >> > The idea would be that instead of getting your individually kmalloc'ed
> >> > elements on-demand from kmalloc while in the handler, you'd get them
> >> > from a pool you've pre-allocated when you set up the table.  This could
> >> > be from a list of individual entries you've already kmalloc'ed ahead of
> >> > time, or from an array of n * sizeof(entry).
> >>
> >> would work, but kinda ugly, since we will pre-allocate a lot
> >> and may not be using it at all.
> >>
> >
> > That's true but you have a user-defined map limit anyway, which you can
> > adjust to minimize wastage.  And allocating ahead of time also means you
> > perturb the system less while actually tracing.
> 
> nope. it's the other way around.
> using kmalloc is faster and less overhead on the whole system
> then grabbing cache-cold objects from special pool.

Until you start causing GFP_ATOMIC failures for what you're tracing
because your map has grabbed them all...

Tom

> --
> 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/


--
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/