From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F139ECAAD5 for ; Mon, 12 Sep 2022 04:37:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EEE9E8D0002; Mon, 12 Sep 2022 00:37:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E9EEE8D0001; Mon, 12 Sep 2022 00:37:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D67448D0002; Mon, 12 Sep 2022 00:37:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id C93E28D0001 for ; Mon, 12 Sep 2022 00:37:22 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 998FB120869 for ; Mon, 12 Sep 2022 04:37:22 +0000 (UTC) X-FDA: 79902174324.16.BD4B51D Received: from mail-pj1-f45.google.com (mail-pj1-f45.google.com [209.85.216.45]) by imf14.hostedemail.com (Postfix) with ESMTP id 41CB3100099 for ; Mon, 12 Sep 2022 04:37:22 +0000 (UTC) Received: by mail-pj1-f45.google.com with SMTP id q62-20020a17090a17c400b00202a3497516so4665690pja.1 for ; Sun, 11 Sep 2022 21:37:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=cWYgHAq5ny4DLQrfpTw7PtOGqiMCf0iPFjcOwcgSxlU=; b=Crz6FiphaYqTlC2dMlFPl+GwYjNz2ePWhRHPifOOZt/mZkbMeSoz4MuYTmF5cUoQNV Ib2DdBKuxKpN4/oSzh9rMu7CwmDjxWe16386T+j6dS3h7wVp0ozBwsgrxdCGHUnw0Xsh r/dfL1YnFAUl4FJS9gBZ8KLZgjLfg5gVm+e1s= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=cWYgHAq5ny4DLQrfpTw7PtOGqiMCf0iPFjcOwcgSxlU=; b=mFCdNHYSxFbVSKGANQycPhjGCnSCgM0heFjb1aBmNj4j433S7L2HnhZvZuA0mjZbQH CPBT8ZAngykkeV1JMyBV5cAOer4SVX2U/BYQulpfMlrdIV1Ro82l7tQpevpEayT6OFB5 ShprjTSFpccyZrXUkxPFet2ICa3Be1cKCNqTF/6551r30yvszay3LXDhBIF4C4m+f2Dk ioVaaBU4NzsIjRc9gLJC/ujL9hp338DDiiT7/Dy2cGtX9PxephC0+nb2ppV9oD2exzvl Rh8PFCSRbaF+ITZpe+EeMKBtnyM0QsuloeOWAHR/zCcIMRf9R4KM1jf93uANkal5dzQK 2K0Q== X-Gm-Message-State: ACgBeo1grqzsKeD5U6CZeU47AmS0q1Z05KAMM1uPyuD4PdEmqd5pEDh3 NlR+wHd3GUChLHs9KV8sZykf/w== X-Google-Smtp-Source: AA6agR4KogsmNIRLD4nHdnmzTog+YMrXg3rCn64hzFxSQEP2+xciQ+EsdoGOUp+jKcNUtuqQoUTISg== X-Received: by 2002:a17:902:a388:b0:176:e571:4923 with SMTP id x8-20020a170902a38800b00176e5714923mr24847717pla.6.1662957441064; Sun, 11 Sep 2022 21:37:21 -0700 (PDT) Received: from google.com ([240f:75:7537:3187:7b09:9fce:b16b:c111]) by smtp.gmail.com with ESMTPSA id 11-20020a63040b000000b004347838b12bsm4431251pge.75.2022.09.11.21.37.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 11 Sep 2022 21:37:20 -0700 (PDT) Date: Mon, 12 Sep 2022 13:37:15 +0900 From: Sergey Senozhatsky To: Brian Geffon , Minchan Kim Cc: Andrew Morton , Nitin Gupta , linux-kernel@vger.kernel.org, Suleiman Souhlal , Rom Lemarchand , linux-mm@kvack.org, Sergey Senozhatsky Subject: Re: [RESEND RFC] zram: Allow rw_page when page isn't written back. Message-ID: References: <20220908125037.1119114-1-bgeffon@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=Crz6Fiph; spf=pass (imf14.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.216.45 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662957442; a=rsa-sha256; cv=none; b=RK1kwhxtkNht46htJtXdWl69YO5PeKhDYj18d/CN6mm98U654LfKE1ahTd+nmMF1TmeZVq JlqrYN2ohnBuy6raVGihbzTp+F2E15q/DxdbryzFKRdKnJGgM2bT+8WYlpGzbJgJetzz9h u19ARPDVUdcDo6cWfDrNVISN48GG5OA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662957442; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=cWYgHAq5ny4DLQrfpTw7PtOGqiMCf0iPFjcOwcgSxlU=; b=xU96yrsUZIXD5jNVJN2vECW54hIhGJTHhoWiRCd37Ny3ktZfj2FgGDb/l2uEnh58q6lxPO yjpWGPFW7QNEyxwQcGNHq7w393Uz4BLn0iB9/McbPMQllnkDQochQiOC36Ih4otYupo9y4 Cx/c/oNwNZVDe27FQIfO+UU/AXoqYnI= X-Stat-Signature: zwmcus5joingd1q6xhjh3gstaf5g899z X-Rspam-User: Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=Crz6Fiph; spf=pass (imf14.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.216.45 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 41CB3100099 X-HE-Tag: 1662957442-98801 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On (22/09/09 17:30), Sergey Senozhatsky wrote: > > +++ b/drivers/block/zram/zram_drv.h > > @@ -50,6 +50,7 @@ enum zram_pageflags { > > ZRAM_UNDER_WB, /* page is under writeback */ > > ZRAM_HUGE, /* Incompressible page */ > > ZRAM_IDLE, /* not accessed page since last idle marking */ > > + ZRAM_NO_WB, /* Do not allow page to be written back */ > > > > __NR_ZRAM_PAGEFLAGS, > > }; > > Unrelated but somehow related. > > I wonder if it's time for us to introduce a dedicated, say u16, > flags member to struct zram_table_entry. Unless my calculations > are extremely wrong, we are about to run out of spare bits in > zram_table_entry::flags on 32-bit systems. Looking at it more - I wonder why do we define ZRAM_FLAG_SHIFT as 24? This is far more than maximum zram object size. Our max size needs PAGE_SHIFT bits (which is normally 12 bits, can be up to 16 (for 64k arm64 pages)). So we probably can start defining ZRAM_FLAG_SHIFT as (PAGE_SHIFT + 1). Or am I missing something? --- diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index b4eecef2a11f..cb8f1f644baf 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -39,7 +39,7 @@ * The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header), * the higher bits is for zram_pageflags. */ -#define ZRAM_FLAG_SHIFT 24 +#define ZRAM_FLAG_SHIFT (PAGE_SHIFT + 1) /* Flags for zram pages (table[page_no].flags) */ enum zram_pageflags {