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Tue, 25 Oct 2022 00:57:11 -0700 (PDT) Date: Tue, 25 Oct 2022 16:57:07 +0900 From: Sergey Senozhatsky To: Andrew Morton Cc: Sergey Senozhatsky , Minchan Kim , Nitin Gupta , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/6] zsmalloc/zram: configurable zspage size Message-ID: References: <20221024161213.3221725-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666684633; a=rsa-sha256; cv=none; b=oANGr6gcAavIoW7x6+cgJt5+aAwRn4A7kAWSYMtQ32JdIHsfgj+qqqnZN7WX3JQ9Uf6Fx0 Co3+n3/siMAnaDUDp/NgV9uzTJ6Gud6W8uOo42PeSL0J3T1e8MfIcR8JPn0M2uatarkdmh L4/hyT8IdeJaRMbljYTKOui0+yIS9OE= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=iCEU9cjq; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf10.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.216.53 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666684633; 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=CwWEryY1wTrlvMcLkLLHD8M1BowwJLAAx+hHBiqXYc0=; b=LSy6KF9jl3gceVcKvkYMHDyIQRdWBGNHVv0gDWDcEKdvhFeCmos4q93qfriv9z0aGxp1cE EcEqiiMcFAyTJNnPOqNWx8DXAnBg8yKmcMTgXwNm+Hu8hKU2t1+iaTiVSpdRG/IOLHtCHT IzFWELGe4rTUOkwl03G5TN+MVGUATUk= X-Rspamd-Queue-Id: 1B3F4C0038 Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=iCEU9cjq; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf10.hostedemail.com: domain of senozhatsky@chromium.org designates 209.85.216.53 as permitted sender) smtp.mailfrom=senozhatsky@chromium.org X-Rspamd-Server: rspam12 X-Rspam-User: X-Stat-Signature: 3qm3t9ujz7pjzhtiu8gem8zb8ucj4jx4 X-HE-Tag: 1666684632-364136 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 (22/10/25 13:30), Sergey Senozhatsky wrote: > On (22/10/25 01:12), Sergey Senozhatsky wrote: > > Sergey Senozhatsky (6): > > zsmalloc: turn zspage order into runtime variable > > zsmalloc/zram: pass zspage order to zs_create_pool() > > zram: add pool_page_order device attribute > > Documentation: document zram pool_page_order attribute > > zsmalloc: break out of loop when found perfect zspage order > > zsmalloc: make sure we select best zspage size > > Andrew, I want to replace the last 2 patches in the series: I think > we can drop `usedpc` calculations and instead optimize only for `waste` > value. Would you prefer me to resend the entire instead? Andrew, let's do it another way - let's drop the last patch from the series. But only the last one. The past was a last minute addition to the series and I have not fully studied it's impact yet. From a preliminary research I can say that it improves zsmalloc memory usage only for order 4 zspages and has no statistically significant impact on order 2 nor order 3 zspages. Synthetic test, base get_pages_per_zspage() vs 'waste' optimized get_pages_per_zspage() for order 4 zspages: x zram-order-4-memused-base + zram-order-4-memused-patched +----------------------------------------------------------------------------+ |+ + + + x xx x| | |___________A_______M____| |____M_A______| | +----------------------------------------------------------------------------+ N Min Max Median Avg Stddev x 4 6.3960678e+08 6.3974605e+08 6.3962726e+08 6.3965082e+08 64101.637 + 4 6.3902925e+08 6.3929958e+08 6.3926682e+08 6.3919514e+08 120652.52 Difference at 95.0% confidence -455680 +/- 167159 -0.0712389% +/- 0.0261329% (Student's t, pooled s = 96607.6) If I will have enough confidence in that patch I will submit it separately, with a proper commit message and clear justification.