From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A51AC7EE23 for ; Thu, 18 May 2023 17:24:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229947AbjERRYG (ORCPT ); Thu, 18 May 2023 13:24:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54388 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229882AbjERRYD (ORCPT ); Thu, 18 May 2023 13:24:03 -0400 Received: from out-62.mta0.migadu.com (out-62.mta0.migadu.com [91.218.175.62]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09B82E7C for ; Thu, 18 May 2023 10:24:01 -0700 (PDT) Date: Thu, 18 May 2023 13:23:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1684430639; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=eK2qQ4usiSIYSyupOId390QtbQqfKan1m34h+LbEFPM=; b=sNDSyKfF6gvVSnJyc248USU5TpD5hQ7R2ejhfCUpcw5itifMC39wJp2ehWtP2bP0CjYZI+ deFH0WplYGLa0sF1XjsHluZnFa8Xv9630WKMzq2MgOCR+jJrtPvpzmwEDCuYnQgr2IfO78 JcTWEMEbSEPgVNsTiwo1CaK0bi5kRFc= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Kent Overstreet To: Song Liu Cc: Mike Rapoport , linux-mm@kvack.org, Andrew Morton , Dave Hansen , Peter Zijlstra , Rick Edgecombe , Thomas Gleixner , Vlastimil Babka , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [RFC PATCH 1/5] mm: intorduce __GFP_UNMAPPED and unmapped_alloc() Message-ID: References: <20230308094106.227365-1-rppt@kernel.org> <20230308094106.227365-2-rppt@kernel.org> <20230518152354.GD4967@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 18, 2023 at 10:00:39AM -0700, Song Liu wrote: > On Thu, May 18, 2023 at 9:48 AM Kent Overstreet > wrote: > > > > On Thu, May 18, 2023 at 09:33:20AM -0700, Song Liu wrote: > > > I am working on patches based on the discussion in [1]. I am planning to > > > send v1 for review in a week or so. > > > > Hey Song, I was reviewing that thread too, > > > > Are you taking a different approach based on Thomas's feedback? I think > > he had some fair points in that thread. > > Yes, the API is based on Thomas's suggestion, like 90% from the discussions. > > > > > My own feeling is that the buddy allocator is our tool for allocating > > larger variable sized physically contiguous allocations, so I'd like to > > see something based on that - I think we could do a hybrid buddy/slab > > allocator approach, like we have for regular memory allocations. > > I am planning to implement the allocator based on this (reuse > vmap_area logic): Ah, you're still doing vmap_area approach. Mike's approach looks like it'll be _much_ lighter weight and higher performance, to me. vmalloc is known to be slow compared to the buddy allocator, and with Mike's approach we're only modifying mappings once per 2 MB chunk. I don't see anything in your code for sub-page sized allocations too, so perhaps I should keep going with my slab allocator. Could you share your thoughts on your approach vs. Mike's? I'm newer to this area of the code than you two so maybe there's an angle I've missed :)