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c=relaxed/relaxed; d=sina.com; s=201208; t=1792925698; bh=4ddGAYAtB79F7wRhnGkW+ljKWe8FQH+MNDzT857Yhzs=; h=From:Subject:Date:Message-ID; b=dwcveCtWjTIJ0cYPZzJoegiSxxeA91p7J90iNFfT7pkuBVicFrRL2T3DZ4G1Lw1l/ cv4n1t8cBnwObK4J4IWd77ZB4pkx8xb9DpgpBjwPXxvHPNIU8uaS1cNVo7Nf3h0ZjI NvMcdtUHzD1fv2txTgYj8zXPhU2b2v4AiBqszo2s= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.246.238.232]) by sina.com (10.54.253.32) with ESMTP id 6ADDDFFB00000221; Sun, 25 Oct 2026 18:54:54 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 6351494456771 X-SMAIL-UIID: 9557747A4C984AC9AE3E1418D8FD2278-20261025-185454-1 From: Hillf Danton To: Sergey Senozhatsky Cc: Barry Song <21cnbao@gmail.com>, Andrew Morton , Brian Geffon , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v6 09/13] zram: split zcomp into separate R/W streams Date: Sun, 25 Oct 2026 18:54:40 +0800 Message-ID: <20261025105441.1148-1-hdanton@sina.com> In-Reply-To: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Sun, 25 Oct 2026 10:38:47 +0900 Sergey Senozhatsky wrote: >On (26/10/24 18:14), Hillf Danton wrote: >> > (PE enabled for all tests) >> > >> > ######## zstd compression level 3 W-vs-R >> > BASE IOPS 1,154k avg 7.84us sd 444us max 697,634us >> > IOPS 881k avg 14.16us sd 2,242us max 1,387,000us >> > IOPS 704k avg 20.43us sd 3,499us max 2,058,300us >> > IOPS 563k avg 29.02us sd 3,910us max 1,649,800us >> > IOPS 626k avg 24.79us sd 4,013us max 2,085,800us >> > IOPS 976k avg 11.54us sd 1,518us max 1,165,800us >> > IOPS 1,178k avg 7.44us sd 22us max 3,103us >> > IOPS 1,120k avg 7.39us sd 21us max 7,222us >> > IOPS 522k avg 32.51us sd 4,311us max 1,598,300us >> > IOPS 581k avg 27.54us sd 3,626us max 1,448,600us >> > IOPS 1,160k avg 7.69us sd 352us max 702,099us >> > IOPS 1,169k avg 7.52us sd 129us max 281,428us >> > IOPS 954k avg 12.06us sd 1,705us max 1,545,600us >> > IOPS 1,029k avg 10.24us sd 1,156us max 976,065us >> > IOPS 1,169k avg 7.48us sd 24us max 4,305us >> > IOPS 1,177k avg 7.45us sd 53us max 118,777us >> > IOPS 579k avg 27.43us sd 3,661us max 1,615,800us >> > IOPS 1,169k avg 7.52us sd 115us max 228,074us >> > IOPS 1,110k avg 8.59us sd 985us max 1,288,000us >> > IOPS 1,177k avg 7.45us sd 29us max 72,245us >> > IOPS 580k avg 27.74us sd 3,755us max 1,507,000us >> > PATCHED IOPS 1,179k avg 7.40us sd 23us max 7,404us >> > IOPS 1,179k avg 7.41us sd 22us max 2,857us >> > IOPS 1,176k avg 7.40us sd 22us max 6,615us >> > IOPS 1,175k avg 7.44us sd 23us max 5,623us >> > IOPS 1,176k avg 7.42us sd 24us max 5,625us >> > IOPS 1,173k avg 7.42us sd 24us max 5,632us >> > IOPS 1,172k avg 7.41us sd 23us max 6,223us >> > IOPS 1,173k avg 7.40us sd 25us max 5,848us >> > IOPS 1,173k avg 7.40us sd 24us max 7,563us >> > IOPS 1,172k avg 7.42us sd 24us max 5,625us >> > IOPS 1,175k avg 7.42us sd 23us max 5,626us >> > IOPS 1,177k avg 7.42us sd 23us max 4,243us >> > IOPS 1,170k avg 7.46us sd 25us max 5,622us >> > IOPS 1,178k avg 7.40us sd 22us max 3,213us >> > IOPS 1,167k avg 7.43us sd 25us max 7,593us >> > IOPS 1,174k avg 7.44us sd 23us max 6,971us >> > IOPS 1,179k avg 7.38us sd 23us max 3,477us >> > IOPS 1,180k avg 7.39us sd 23us max 2,894us >> > IOPS 1,145k avg 7.37us sd 21us max 4,048us >> > IOPS 1,177k avg 7.38us sd 22us max 5,620us >> > IOPS 1,177k avg 7.40us sd 23us max 5,623us >> > >> > IOPS: BASE 932k (+-260k), PATCHED 1,174k (+-7k), 21 runs each. >> > significant difference at 95% confidence: PATCHED is 241k (25.9%) higher; 95% CI [+136k, +353k], Welch's t-test p = 0.000 >> > max latency: BASE 3.1..2,085.8 ms, PATCHED 2.9..7.6 ms >> > runs with max over 100 ms: BASE 17 of 21, PATCHED 0 of 21; over 1 s: BASE 11 of 21, PATCHED 0 of 21 >> > >> > ######## zstd compression level 12 W-vs-R >> > BASE IOPS 690k avg 21.53us sd 3,088us max 1,635,500us >> > IOPS 478k avg 36.51us sd 4,385us max 1,941,300us >> > IOPS 822k avg 16.13us sd 2,865us max 2,263,800us >> > IOPS 1,161k avg 7.73us sd 114us max 190,307us >> > IOPS 780k avg 17.56us sd 2,717us max 1,550,500us >> > IOPS 1,166k avg 7.66us sd 40us max 94,522us >> > IOPS 585k avg 27.51us sd 3,847us max 1,550,600us >> > IOPS 1,147k avg 7.97us sd 344us max 496,483us >> > IOPS 1,166k avg 7.64us sd 49us max 115,243us >> > IOPS 1,163k avg 7.66us sd 23us max 7,006us >> > IOPS 1,071k avg 9.42us sd 1,489us max 1,915,500us >> > IOPS 962k avg 11.88us sd 2,168us max 1,904,500us >> > IOPS 607k avg 26.05us sd 3,538us max 1,591,100us >> > IOPS 1,167k avg 7.63us sd 23us max 2,903us >> > IOPS 1,157k avg 7.78us sd 198us max 418,930us >> > IOPS 1,163k avg 7.66us sd 40us max 100,346us >> > IOPS 1,162k avg 7.70us sd 32us max 82,602us >> > IOPS 488k avg 35.43us sd 4,340us max 1,786,400us >> > IOPS 563k avg 28.85us sd 3,989us max 2,209,500us >> > IOPS 843k avg 15.43us sd 2,490us max 1,572,100us >> > IOPS 604k avg 26.30us sd 3,560us max 1,555,700us >> > PATCHED IOPS 1,166k avg 7.60us sd 23us max 5,623us >> > IOPS 1,169k avg 7.58us sd 23us max 5,629us >> > IOPS 1,157k avg 7.67us sd 27us max 5,639us >> > IOPS 1,166k avg 7.61us sd 24us max 5,644us >> > IOPS 1,160k avg 7.64us sd 26us max 7,543us >> > IOPS 1,167k avg 7.60us sd 24us max 7,514us >> > IOPS 1,160k avg 7.61us sd 25us max 6,643us >> > IOPS 1,162k avg 7.65us sd 25us max 7,315us >> > IOPS 1,161k avg 7.66us sd 24us max 6,237us >> > IOPS 1,158k avg 7.62us sd 27us max 7,688us >> > IOPS 1,167k avg 7.58us sd 24us max 5,637us >> > IOPS 1,165k avg 7.59us sd 24us max 7,098us >> > IOPS 948k avg 7.58us sd 23us max 7,808us >> > IOPS 1,166k avg 7.60us sd 24us max 5,621us >> > IOPS 1,166k avg 7.58us sd 24us max 5,672us >> > IOPS 1,162k avg 7.65us sd 25us max 6,824us >> > IOPS 1,165k avg 7.59us sd 24us max 7,078us >> > IOPS 1,168k avg 7.58us sd 23us max 6,191us >> > IOPS 1,170k avg 7.56us sd 22us max 2,851us >> > IOPS 1,171k avg 7.55us sd 22us max 2,834us >> > IOPS 1,166k avg 7.59us sd 24us max 5,627us >> > >> > IOPS: BASE 902k (+-269k), PATCHED 1,154k (+-47k), 21 runs each. >> > significant difference at 95% confidence: PATCHED is 252k (27.9%) higher; 95% CI [+142k, +367k], Welch's t-test p = 0.000 >> > max latency: BASE 2.9..2,263.8 ms, PATCHED 2.8..7.8 ms >> > runs with max over 100 ms: BASE 17 of 21, PATCHED 0 of 21; over 1 s: BASE 12 of 21, PATCHED 0 of 21 >> > >> > ######## lz4 W-vs-R >> > BASE IOPS 1,422k avg 3.84us sd 418us max 619,495us >> > IOPS 1,450k avg 3.57us sd 326us max 609,723us >> > IOPS 1,414k avg 3.92us sd 543us max 879,815us >> > IOPS 1,451k avg 3.56us sd 253us max 503,428us >> > IOPS 1,460k avg 3.40us sd 68us max 135,825us >> > IOPS 1,413k avg 3.31us sd 44us max 188,450us >> > IOPS 1,432k avg 3.73us sd 503us max 844,228us >> > IOPS 1,387k avg 4.20us sd 719us max 961,827us >> > IOPS 1,464k avg 3.38us sd 44us max 133,675us >> > IOPS 1,469k avg 3.38us sd 22us max 65,812us >> > IOPS 1,465k avg 3.40us sd 49us max 111,788us >> > IOPS 1,465k avg 3.39us sd 64us max 174,040us >> > IOPS 1,467k avg 3.38us sd 36us max 97,821us >> > IOPS 1,445k avg 3.63us sd 343us max 671,026us >> > IOPS 1,472k avg 3.35us sd 27us max 86,795us >> > IOPS 1,473k avg 3.33us sd 44us max 138,096us >> > IOPS 1,439k avg 3.71us sd 353us max 619,815us >> > IOPS 1,398k avg 3.36us sd 54us max 206,815us >> > IOPS 1,471k avg 3.36us sd 15us max 2,832us >> > IOPS 1,407k avg 4.02us sd 629us max 1,074,800us >> > IOPS 1,465k avg 3.40us sd 63us max 158,779us >> > PATCHED IOPS 1,471k avg 3.30us sd 15us max 6,946us >> > IOPS 1,473k avg 3.29us sd 16us max 5,618us >> > IOPS 1,474k avg 3.29us sd 15us max 5,615us >> > IOPS 1,473k avg 3.29us sd 15us max 5,625us >> > IOPS 1,440k avg 3.26us sd 13us max 2,829us >> > IOPS 1,456k avg 3.30us sd 15us max 5,623us >> > IOPS 1,476k avg 3.29us sd 15us max 2,835us >> > IOPS 1,464k avg 3.28us sd 16us max 6,063us >> > IOPS 1,468k avg 3.32us sd 19us max 6,692us >> > IOPS 1,465k avg 3.30us sd 17us max 6,834us >> > IOPS 1,468k avg 3.28us sd 16us max 7,268us >> > IOPS 1,463k avg 3.31us sd 17us max 6,480us >> > IOPS 1,454k avg 3.33us sd 20us max 8,418us >> > IOPS 1,452k avg 3.32us sd 19us max 5,621us >> > IOPS 1,477k avg 3.27us sd 14us max 2,834us >> > IOPS 1,468k avg 3.30us sd 16us max 5,617us >> > IOPS 1,475k avg 3.30us sd 16us max 3,884us >> > IOPS 1,475k avg 3.30us sd 16us max 5,692us >> > IOPS 1,471k avg 3.30us sd 15us max 5,616us >> > IOPS 1,473k avg 3.28us sd 16us max 7,014us >> > IOPS 1,475k avg 3.28us sd 15us max 5,616us >> > >> > IOPS: BASE 1,444k (+-27k), PATCHED 1,467k (+-10k), 21 runs each. >> > significant difference at 95% confidence: PATCHED is 23k (1.6%) higher; 95% CI [+11k, +35k], Welch's t-test p = 0.001 >> > max latency: BASE 2.8..1,074.8 ms, PATCHED 2.8..8.4 ms >> > runs with max over 100 ms: BASE 17 of 21, PATCHED 0 of 21; over 1 s: BASE 1 of 21, PATCHED 0 of 21 >> >> >> Lets see the data from another pov (feel free to disagree) -- in the android >> phone/car cockpit environment, the render frequence is required above 60HZ, >> IOW a frame rendered within 16ms, so what share of the 16ms does the IOPS >> account for after this patchset, for example when an app in background is >> brought foreground? > > A single 500 ms read stall is 30 dropped frames. Across 126 runs that > I ran, base+PE had read stalls over 100 ms in 108 runs and over 1 s in 47. > The worst read with the series+PE, in all 126 runs, was 8.4 ms, i.e. within > one frame. > Good work from the 2026 most valuable baker, MVB. Hillf