From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Jeff Moyer Subject: Re: Problems with VM_MIXEDMAP removal from /proc//smaps References: <20181002100531.GC4135@quack2.suse.cz> <20181016082540.GA18918@quack2.suse.cz> Date: Tue, 16 Oct 2018 08:35:00 -0400 In-Reply-To: <20181016082540.GA18918@quack2.suse.cz> (Jan Kara's message of "Tue, 16 Oct 2018 10:25:40 +0200") Message-ID: MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org To: Jan Kara Cc: Dan Williams , Dave Jiang , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org List-ID: Jan Kara writes: > Hi Jeff, > > On Tue 09-10-18 15:43:41, Jeff Moyer wrote: >> I'm intrigued by the use case. Do I understand you correctly that the >> database in question does not intend to make data persistent from >> userspace? In other words, fsync/msync system calls are being issued by >> the database? > > Yes, at least at the initial stage, they use fsync / msync to persist data. OK. >> I guess what I'm really after is a statement of requirements or >> expectations. It would be great if you could convince the database >> developer to engage in this discussion directly. > > So I talked to them and what they really look after is the control over the > amount of memory needed by the kernel. And they are right that if your > storage needs page cache, the amount of memory you need to set aside for the > kernel is larger. OK, thanks a lot for following up, Jan! -Jeff