From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f47.google.com (mail-pa0-f47.google.com [209.85.220.47]) by kanga.kvack.org (Postfix) with ESMTP id 970A66B0005 for ; Wed, 17 Feb 2016 23:45:26 -0500 (EST) Received: by mail-pa0-f47.google.com with SMTP id fy10so23658411pac.1 for ; Wed, 17 Feb 2016 20:45:26 -0800 (PST) Received: from mail-pf0-x22e.google.com (mail-pf0-x22e.google.com. [2607:f8b0:400e:c00::22e]) by mx.google.com with ESMTPS id w12si6690574pfa.177.2016.02.17.20.45.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Feb 2016 20:45:26 -0800 (PST) Received: by mail-pf0-x22e.google.com with SMTP id c10so24823143pfc.2 for ; Wed, 17 Feb 2016 20:45:25 -0800 (PST) Date: Thu, 18 Feb 2016 13:46:42 +0900 From: Sergey Senozhatsky Subject: Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Message-ID: <20160218044642.GB10776@swordfish> References: <1455764556-13979-1-git-send-email-sergey.senozhatsky@gmail.com> <1455764556-13979-4-git-send-email-sergey.senozhatsky@gmail.com> <20160218044156.GA10776@swordfish> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160218044156.GA10776@swordfish> Sender: owner-linux-mm@kvack.org List-ID: To: Sergey Senozhatsky Cc: Andrew Morton , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky On (02/18/16 13:41), Sergey Senozhatsky wrote: > I think we better switch to different logic here -- specify how many ->huge > classes we want to have, and let zsmalloc to calculate ZS_MAX_PAGES_PER_ZSPAGE. > > > For example, if we want to have 20 ->huge classes, the 'smallest' (or the last) ^^^ largest > non-huge class will have CLASS_SIZE * SIZE_CLASS_DELTA of spare (wasted) space, > so PAGE_SIZE / (CLASS_SIZE * SIZE_CLASS_DELTA) will give us the number of pages > we need to form into a zspage to make it the last huge class. ^^ 'non-huge'... what is the correct english word I'm looking for... -ss > setting ZS_MIN_HUGE_CLASSES_NUM to 32 gives us (on x86_64, PAGE_SHIFT 12) ->huge > class size range of [3648, 4096]. so all objects smaller than 3648 will not waste > an entire zspage (and order-0 page), but will share the page with another objects > of that size. > > > something like this: > > --- > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index 0c9f117..d5252d1 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -73,12 +73,6 @@ > */ > #define ZS_ALIGN 8 > > -/* > - * A single 'zspage' is composed of up ZS_MAX_PAGES_PER_ZSPAGE discontiguous > - * 0-order (single) pages. > - */ > -#define ZS_MAX_PAGES_PER_ZSPAGE 6 > - > #define ZS_HANDLE_SIZE (sizeof(unsigned long)) > > /* > @@ -149,6 +143,21 @@ > #define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8) > > /* > + * We want to have at least this number of ->huge classes. > + */ > +#define ZS_MIN_HUGE_CLASSES_NUM 32 > +/* > + * A single 'zspage' is composed of up ZS_MAX_PAGES_PER_ZSPAGE discontiguous > + * 0-order (single) pages. > + * > + * The smallest huge class will have CLASS_SIZE * SIZE_CLASS_DELTA of > + * wasted space, calculate how many pages we need to fit a CLASS_SIZE > + * object there and, thus, to save a additional zspage. > + */ > +#define ZS_MAX_PAGES_PER_ZSPAGE \ > + (PAGE_SIZE / (ZS_MIN_HUGE_CLASSES_NUM * ZS_SIZE_CLASS_DELTA)) > + > +/* > * We do not maintain any list for completely empty or full pages > */ > enum fullness_group { > -- 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