From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752417AbeDSI2W (ORCPT ); Thu, 19 Apr 2018 04:28:22 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:38342 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750937AbeDSI2T (ORCPT ); Thu, 19 Apr 2018 04:28:19 -0400 Date: Thu, 19 Apr 2018 01:28:10 -0700 From: Christoph Hellwig To: Yang Shi Cc: Christoph Hellwig , viro@zeniv.linux.org.uk, nyc@holomorphy.com, mike.kravetz@oracle.com, kirill.shutemov@linux.intel.com, hughd@google.com, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] fs: introduce ST_HUGE flag and set it to tmpfs and hugetlbfs Message-ID: <20180419082810.GA8624@infradead.org> References: <1523999293-94152-1-git-send-email-yang.shi@linux.alibaba.com> <20180418102744.GA10397@infradead.org> <73090d4b-6831-805b-8b9d-5dff267428d9@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <73090d4b-6831-805b-8b9d-5dff267428d9@linux.alibaba.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 18, 2018 at 11:18:25AM -0700, Yang Shi wrote: > Yes, thanks for the suggestion. I did think about it before I went with the > new flag. Not like hugetlb, THP will *not* guarantee huge page is used all > the time, it may fallback to regular 4K page or may get split. I'm not sure > how the applications use f_bsize field, it might break existing applications > and the value might be abused by applications to have counter optimization. > So, IMHO, a new flag may sound safer. But st_blksize isn't the block size, that is why I suggested it. It is the preferred I/O size, and various file systems can report way larger values than the block size already.