From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1526354953; cv=none; d=google.com; s=arc-20160816; b=gS6BfxVbk46yhTlyBX+8Jj5brXveMqQzwkBcBq0RqhtjVN4C8GX5hrlI0Z3bv6H3SP LxWKQ+u+2HJ3mRU759pKf9cRUVo4crYczPuFs0TpINWNrwNCDynck5JUjHC1Z2sW+wcc /CQCeW+c2qFAEDFijB+TZPZN2cJfnQiH+GEeBwcF68U3BV13oDpFflK+hfNmf90mCeRh 8TfMlmrBUczqlcFwVu5mpmk5XIeAGkagDp22Ltum2AlBY7u9E9MGAT0vI/Gg2QTomJQJ 0D/08jXD/8MiybKRnK6qnDeQMYhnPpj0xKrBdH1wZVTl92hfcNj6v7x+zVTfeL2B7fw+ d9ig== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:dkim-signature:arc-authentication-results; bh=2Lj4naZtZqt9irH9/MoqsnFeZIJXiLGfMZqBHu0zp2U=; b=o7dHe8qNNmXqxkP/k4zW9ESHv1sKhDZIqyUpgtxGo0o/4w8PyMwgLpUWdzE21TziNy 8rMPZPP+wO7O437FyV7DRNxiM1nZaGhB4bSwLdFS0M7m2mlDOBCXJ1br5BykMfF6OSTp MFtu839WVMpqqWCT3GRQbxUf1SCRP1gtn9rQ5iPL+qMUKBY7j0Ae0ODrj/dSovvAyWDQ /HAWn0mRxCC/2jpJIzNqkI38O64IRnQsH037JWJORYDSalnNw47cO6cjxa2RjKMaskFD YC46aPvjUUQEzAV0eDEdch7rpPS2G1OI4exvW9VvkEofy3XPv8p5LrfI7sEUtsVEnBYH 9ENw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=sXepanG6; spf=pass (google.com: domain of vdavydov.dev@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=vdavydov.dev@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=sXepanG6; spf=pass (google.com: domain of vdavydov.dev@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=vdavydov.dev@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AB8JxZrkDJpM96GqwB0EqMmDhqhMnaboJcU2ymHhRyIY9OqcbTFvqNm9ik1kSbeAAw+5ugF7TdF1wg== Date: Tue, 15 May 2018 06:29:09 +0300 From: Vladimir Davydov To: Kirill Tkhai Cc: akpm@linux-foundation.org, shakeelb@google.com, viro@zeniv.linux.org.uk, hannes@cmpxchg.org, mhocko@kernel.org, tglx@linutronix.de, pombredanne@nexb.com, stummala@codeaurora.org, gregkh@linuxfoundation.org, sfr@canb.auug.org.au, guro@fb.com, mka@chromium.org, penguin-kernel@I-love.SAKURA.ne.jp, chris@chris-wilson.co.uk, longman@redhat.com, minchan@kernel.org, ying.huang@intel.com, mgorman@techsingularity.net, jbacik@fb.com, linux@roeck-us.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, lirongqing@baidu.com, aryabinin@virtuozzo.com Subject: Re: [PATCH v5 01/13] mm: Assign id to every memcg-aware shrinker Message-ID: <20180515032909.kjbhxxg7463nnvwo@esperanza> References: <152594582808.22949.8353313986092337675.stgit@localhost.localdomain> <152594593798.22949.6730606876057040426.stgit@localhost.localdomain> <20180513051509.df2tcmbhxn3q2fp7@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1599987539736036809?= X-GMAIL-MSGID: =?utf-8?q?1600499170988223506?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Mon, May 14, 2018 at 12:03:38PM +0300, Kirill Tkhai wrote: > On 13.05.2018 08:15, Vladimir Davydov wrote: > > On Thu, May 10, 2018 at 12:52:18PM +0300, Kirill Tkhai wrote: > >> The patch introduces shrinker::id number, which is used to enumerate > >> memcg-aware shrinkers. The number start from 0, and the code tries > >> to maintain it as small as possible. > >> > >> This will be used as to represent a memcg-aware shrinkers in memcg > >> shrinkers map. > >> > >> Since all memcg-aware shrinkers are based on list_lru, which is per-memcg > >> in case of !SLOB only, the new functionality will be under MEMCG && !SLOB > >> ifdef (symlinked to CONFIG_MEMCG_SHRINKER). > > > > Using MEMCG && !SLOB instead of introducing a new config option was done > > deliberately, see: > > > > http://lkml.kernel.org/r/20151210202244.GA4809@cmpxchg.org > > > > I guess, this doesn't work well any more, as there are more and more > > parts depending on kmem accounting, like shrinkers. If you really want > > to introduce a new option, I think you should call it CONFIG_MEMCG_KMEM > > and use it consistently throughout the code instead of MEMCG && !SLOB. > > And this should be done in a separate patch. > > What do you mean under "consistently throughout the code"? Should I replace > all MEMCG && !SLOB with CONFIG_MEMCG_KMEM over existing code? Yes, otherwise it looks messy - in some places we check !SLOB, in others we use CONFIG_MEMCG_SHRINKER (or whatever it will be called). > > >> diff --git a/fs/super.c b/fs/super.c > >> index 122c402049a2..16c153d2f4f1 100644 > >> --- a/fs/super.c > >> +++ b/fs/super.c > >> @@ -248,6 +248,9 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags, > >> s->s_time_gran = 1000000000; > >> s->cleancache_poolid = CLEANCACHE_NO_POOL; > >> > >> +#ifdef CONFIG_MEMCG_SHRINKER > >> + s->s_shrink.id = -1; > >> +#endif > > > > No point doing that - you are going to overwrite the id anyway in > > prealloc_shrinker(). > > Not so, this is done deliberately. alloc_super() has the only "fail" label, > and it handles all the allocation errors there. The patch just behaves in > the same style. It sets "-1" to make destroy_unused_super() able to differ > the cases, when shrinker is really initialized, and when it's not. > If you don't like this, I can move "s->s_shrink.id = -1;" into > prealloc_memcg_shrinker() instead of this. Yes, please do so that we don't have MEMCG ifdefs in fs code. Thanks.