From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932182AbbCBWEQ (ORCPT ); Mon, 2 Mar 2015 17:04:16 -0500 Received: from mga09.intel.com ([134.134.136.24]:13430 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932099AbbCBWEH (ORCPT ); Mon, 2 Mar 2015 17:04:07 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,677,1418112000"; d="scan'208";a="659442952" Message-ID: <1425333845.20819.60.camel@picadillo> Subject: Re: [PATCH 07/15] mm: Add ___GFP_NOTRACE From: Tom Zanussi To: Alexei Starovoitov Cc: Steven Rostedt , Masami Hiramatsu , Namhyung Kim , Andi Kleen , LKML Date: Mon, 02 Mar 2015 16:04:05 -0600 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-4.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2015-03-02 at 11:29 -0800, Alexei Starovoitov wrote: > On Mon, Mar 2, 2015 at 10:54 AM, Tom Zanussi > 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@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/