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[192.55.52.43]) by mx.google.com with ESMTPS id m3si1023742pld.40.2019.05.29.14.43.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 29 May 2019 14:43:28 -0700 (PDT) Received-SPF: pass (google.com: domain of ira.weiny@intel.com designates 192.55.52.43 as permitted sender) client-ip=192.55.52.43; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ira.weiny@intel.com designates 192.55.52.43 as permitted sender) smtp.mailfrom=ira.weiny@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 May 2019 14:43:27 -0700 X-ExtLoop1: 1 Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by fmsmga001.fm.intel.com with ESMTP; 29 May 2019 14:43:27 -0700 Date: Wed, 29 May 2019 14:44:30 -0700 From: Ira Weiny To: Matthew Wilcox Cc: "linux-mm@kvack.org" Subject: Re: [RFC 00/11] Remove 'order' argument from many mm functions Message-ID: <20190529214428.GA1543@iweiny-DESK2.sc.intel.com> References: <20190507040609.21746-1-willy@infradead.org> <20190509015809.GB26131@iweiny-DESK2.sc.intel.com> <20190509140713.GB23561@bombadil.infradead.org> <2807E5FD2F6FDA4886F6618EAC48510E79D0CFDA@CRSMSX101.amr.corp.intel.com> <20190509182902.GA11738@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190509182902.GA11738@bombadil.infradead.org> User-Agent: Mutt/1.11.1 (2018-12-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, May 09, 2019 at 11:29:02AM -0700, Matthew Wilcox wrote: > On Thu, May 09, 2019 at 04:48:39PM +0000, Weiny, Ira wrote: > > > On Wed, May 08, 2019 at 06:58:09PM -0700, Ira Weiny wrote: > > > > On Mon, May 06, 2019 at 09:05:58PM -0700, Matthew Wilcox wrote: > > > > > It's possible to save a few hundred bytes from the kernel text by > > > > > moving the 'order' argument into the GFP flags. I had the idea > > > > > while I was playing with THP pagecache (notably, I didn't want to add an > > > 'order' > > > > > parameter to pagecache_get_page()) > > > ... > > > > > Anyway, this is just a quick POC due to me being on an aeroplane for > > > > > most of today. Maybe we don't want to spend five GFP bits on this. > > > > > Some bits of this could be pulled out and applied even if we don't > > > > > want to go for the main objective. eg rmqueue_pcplist() doesn't use > > > > > its gfp_flags argument. > > > > > > > > Over all I may just be a simpleton WRT this but I'm not sure that the > > > > added complexity justifies the gain. > > > > > > I'm disappointed that you see it as added complexity. I see it as reducing > > > complexity. With this patch, we can simply pass GFP_PMD as a flag to > > > pagecache_get_page(); without it, we have to add a fifth parameter to > > > pagecache_get_page() and change all the callers to pass '0'. > > > > I don't disagree for pagecache_get_page(). > > > > I'm not saying we should not do this. But this seems odd to me. > > > > Again I'm probably just being a simpleton... > > This concerns me, though. I see it as being a simplification, but if > other people see it as a complication, then it's not. Perhaps I didn't > take the patches far enough for you to see benefit? We have quite the > thicket of .*alloc_page.* functions, and I can't keep them all straight. > Between taking, or not taking, the nodeid, the gfp mask, the order, a VMA > and random other crap; not to mention the NUMA vs !NUMA implementations, > this is crying out for simplification. Was there a new version of this coming? Sorry perhaps I dropped the ball here by not replying? Ira > > It doesn't help that I screwed up the __get_free_pages patch. I should > have grepped and realised that we had over 200 callers and it's not > worth changing them all as part of this patchset. >