From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa0-f47.google.com (mail-oa0-f47.google.com [209.85.219.47]) by kanga.kvack.org (Postfix) with ESMTP id 318D56B0031 for ; Mon, 7 Apr 2014 18:14:22 -0400 (EDT) Received: by mail-oa0-f47.google.com with SMTP id i11so94360oag.20 for ; Mon, 07 Apr 2014 15:14:21 -0700 (PDT) Received: from mail-ob0-x230.google.com (mail-ob0-x230.google.com [2607:f8b0:4003:c01::230]) by mx.google.com with ESMTPS id be9si53916obb.103.2014.04.07.15.14.21 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 07 Apr 2014 15:14:21 -0700 (PDT) Received: by mail-ob0-f176.google.com with SMTP id wp18so88622obc.35 for ; Mon, 07 Apr 2014 15:14:21 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <5342F083.5020509@linaro.org> References: <1395436655-21670-1-git-send-email-john.stultz@linaro.org> <1395436655-21670-3-git-send-email-john.stultz@linaro.org> <5342F083.5020509@linaro.org> From: KOSAKI Motohiro Date: Mon, 7 Apr 2014 18:14:01 -0400 Message-ID: Subject: Re: [PATCH 2/5] vrange: Add purged page detection on setting memory non-volatile Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: John Stultz Cc: LKML , Andrew Morton , Android Kernel Team , Johannes Weiner , Robert Love , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Dmitry Adamushko , Neil Brown , Andrea Arcangeli , Mike Hommey , Taras Glek , Jan Kara , Michel Lespinasse , Minchan Kim , "linux-mm@kvack.org" >> This change hwpoison and migration tag number. maybe ok, maybe not. > > Though depending on config can't these tag numbers change anyway? I don't think distro disable any of these. >> I'd suggest to use younger number than hwpoison. >> (That's why hwpoison uses younger number than migration) > > So I can, but the way these are defined makes the results seem pretty > terrible: > > #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + SWP_HWPOISON_NUM \ > + SWP_MVOLATILE_PURGED_NUM + 1) > > Particularly when: > #define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT) \ > - SWP_MIGRATION_NUM \ > - SWP_HWPOISON_NUM \ > - SWP_MVOLATILE_PURGED_NUM \ > ) > > Its a lot of unnecessary mental gymnastics. Yuck. > > Would a general cleanup like the following be ok to try to make this > more extensible? > > thanks > -john > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 3507115..21387df 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -49,29 +49,38 @@ static inline int current_is_kswapd(void) > * actions on faults. > */ > > +enum { > + /* > + * NOTE: We use the high bits here (subtracting from > + * 1< + * new entries here at the top of the enum, not at the bottom > + */ > +#ifdef CONFIG_MEMORY_FAILURE > + SWP_HWPOISON_NR, > +#endif > +#ifdef CONFIG_MIGRATION > + SWP_MIGRATION_READ_NR, > + SWP_MIGRATION_WRITE_NR, > +#endif > + SWP_MAX_NR, > +}; > +#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT) - SWP_MAX_NR) > + I don't see any benefit of this code. At least, SWP_MAX_NR is suck. The name doesn't match the actual meanings. -- 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