From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f72.google.com (mail-it0-f72.google.com [209.85.214.72]) by kanga.kvack.org (Postfix) with ESMTP id F34D1280850 for ; Sun, 21 May 2017 08:58:48 -0400 (EDT) Received: by mail-it0-f72.google.com with SMTP id l145so62539168ita.14 for ; Sun, 21 May 2017 05:58:48 -0700 (PDT) Received: from aserp1040.oracle.com (aserp1040.oracle.com. [141.146.126.69]) by mx.google.com with ESMTPS id x127si29862850itb.55.2017.05.21.05.58.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 21 May 2017 05:58:48 -0700 (PDT) Subject: Re: [v4 1/1] mm: Adaptive hash table scaling References: <1495300013-653283-1-git-send-email-pasha.tatashin@oracle.com> <1495300013-653283-2-git-send-email-pasha.tatashin@oracle.com> <87h90faroe.fsf@firstfloor.org> From: Pasha Tatashin Message-ID: Date: Sun, 21 May 2017 08:58:25 -0400 MIME-Version: 1.0 In-Reply-To: <87h90faroe.fsf@firstfloor.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andi Kleen Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org Hi Andi, Thank you for looking at this. I mentioned earlier, I would not want to impose a cap. However, if you think that for example dcache needs a cap, there is already a mechanism for that via high_limit argument, so the client can be changed to provide that cap. However, this particular patch addresses scaling problem for everyone by making it scale with memory at a slower pace. Thank you, Pasha On 05/20/2017 10:07 PM, Andi Kleen wrote: > Pavel Tatashin writes: > >> Allow hash tables to scale with memory but at slower pace, when HASH_ADAPT >> is provided every time memory quadruples the sizes of hash tables will only >> double instead of quadrupling as well. This algorithm starts working only >> when memory size reaches a certain point, currently set to 64G. >> >> This is example of dentry hash table size, before and after four various >> memory configurations: > > IMHO the scale is still too aggressive. I find it very unlikely > that a 1TB machine really needs 256MB of hash table because > number of used files are unlikely to directly scale with memory. > > Perhaps should just cap it at some large size, e.g. 32M > > -Andi > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org