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Fri, 04 Nov 2022 00:53:17 -0700 (PDT) Date: Fri, 4 Nov 2022 16:53:13 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Andrew Morton , Nitin Gupta , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv4 4/9] zram: Introduce recompress sysfs knob Message-ID: References: <20221018045533.2396670-1-senozhatsky@chromium.org> <20221018045533.2396670-5-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667548399; 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=Zup+uRlcf7AhU3cAwCzxwDKZNLa4muKa6BvILHvv3H8=; b=gdIr4V2pQIdyzJAVDAbSqAYoEMXxDVSwUr84YisbFP3+MEdRysvyRP+EBJE1Db3niw50ec 3BGhYz13/T4ekGLFjSCkqt+vryj7+i9S+5MYFKrzO9bY3+7pOgnMI/7FCdYGBCqG2A1/Lq kE0wMp38+AyD4fqhTwx2SAIEG2xpbpU= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=IFZopsVs; spf=pass (imf07.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.215.173 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=1667548399; a=rsa-sha256; cv=none; b=3H3b5UYnzDyVcCWnQCBHBpAgB/Tp/jE3DeOKk2d9ZAzeO911W1pgKm0K9rHbFty5jFgBF1 AcOvrITNPT/GjJ3fbk1pn7OnPFyOysBGyEtjsAh41/mDQHTn0U3gvELo2CYQSRiKyNFCyP fr16tWxE91zfP+6fIIVNet7wkaNQOcA= Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=IFZopsVs; spf=pass (imf07.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.215.173 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Stat-Signature: w7d8osuetikeydbxba9un97ooa51uxe4 X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 3ABF940006 X-HE-Tag: 1667548399-412892 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On (22/11/03 10:00), Minchan Kim wrote: > zram->table[index].flags > > If we squeeze the algorithm index, we could work like this > without ZRAM_RECOMP_SKIP. Something like this? Allocate two ->flags bits for priority and one bit for RECOMP_SKIP. Two priority bits let us to have 3 alternative algorithms (01 10 11) plus one default (00). So 4 in total. --- diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 12f03745baf9..af0ff58087ca 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -127,6 +127,19 @@ static size_t zram_get_obj_size(struct zram *zram, u32 index) return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1); } +static inline void zram_set_priority(struct zram *zram, u32 index, u32 prio) +{ + prio &= ZRAM_COMP_PRIORITY_MASK; + zram->table[index].flags &= (prio << ZRAM_COMP_PRIORITY_1); +} + +static inline u32 zram_get_priority(struct zram *zram, u32 index) +{ + u32 prio = zram->table[index].flags; + + return prio & ZRAM_COMP_PRIORITY_MASK; +} + static void zram_set_obj_size(struct zram *zram, u32 index, size_t size) { diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index bdfc9bf0bdd5..33e52c5a9a90 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -40,6 +40,8 @@ */ #define ZRAM_FLAG_SHIFT (PAGE_SHIFT + 1) +#define ZRAM_COMP_PRIORITY_MASK 0x3 + /* Flags for zram pages (table[page_no].flags) */ enum zram_pageflags { /* zram slot is locked */ @@ -49,8 +51,9 @@ enum zram_pageflags { ZRAM_UNDER_WB, /* page is under writeback */ ZRAM_HUGE, /* Incompressible page */ ZRAM_IDLE, /* not accessed page since last idle marking */ - ZRAM_RECOMP, /* page was recompressed */ ZRAM_RECOMP_SKIP, /* secondary algorithm cannot compress this page */ + ZRAM_COMP_PRIORITY_1, + ZRAM_COMP_PRIORITY_2, __NR_ZRAM_PAGEFLAGS, };