From mboxrd@z Thu Jan 1 00:00:00 1970 From: "U.Mutlu" Subject: Re: [RFC PATCH v2 RESEND] drivers: ata: ahci_sunxi: Increased SATA/AHCI DMA TX/RX FIFOs Date: Mon, 13 May 2019 13:20:52 +0200 Message-ID: <5CD95314.4060307@mutluit.com> References: <20190512205954.18435-1-um@mutluit.com> <20190513095916.yyjdtueeefkf4v4b@flea> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190513095916.yyjdtueeefkf4v4b@flea> Sender: linux-kernel-owner@vger.kernel.org To: Maxime Ripard Cc: Jens Axboe , Chen-Yu Tsai , linux-ide@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com, linux-amarula@amarulasolutions.com, Jagan Teki , Pablo Greco , Mark Rutland , Oliver Schinagl , Linus Walleij , Hans de Goede , FUKAUMI Naoki , Andre Przywara , Stefan Monnier List-Id: linux-ide@vger.kernel.org Maxime Ripard wrote on 05/13/2019 11:59 AM: > On Sun, May 12, 2019 at 10:59:54PM +0200, Uenal Mutlu wrote: >> Increasing the SATA/AHCI DMA TX/RX FIFOs (P0DMACR.TXTS and .RXTS, ie. >> TX_TRANSACTION_SIZE and RX_TRANSACTION_SIZE) from default 0x0 each >> to 0x3 each, gives a write performance boost of 120 MiB/s to 132 MiB/s >> from lame 36 MiB/s to 45 MiB/s previously. >> Read performance is about 200 MiB/s. >> [tested on SSD using dd bs=2K/4K/8K/12K/16K/24K/32K: peak-perf at 12K]. >> >> Tested on the Banana Pi R1 (aka Lamobo R1) and Banana Pi M1 SBCs >> with Allwinner A20 32bit-SoCs (ARMv7-a / arm-linux-gnueabihf). >> These devices are RaspberryPi-like small devices. >> >> This problem of slow SATA write-speed with these small devices lasts now >> for more than 5 years. Many commentators throughout the years wrongly >> assumed the slow write speed was a hardware limitation. This patch finally >> solves the problem, which in fact was just a hard-to-fix software problem >> (b/c of lack of documentation by the SoC-maker Allwinner Technology). >> >> RFC: Since more than about 25 similar SBC/SoC models do use the >> ahci_sunxi driver, users are encouraged to test it on all the >> affected boards and give feedback. >> >> Lists of the affected sunxi and other boards and SoCs with SATA using >> the ahci_sunxi driver: >> $ grep -i -e "^&ahci" arch/arm/boot/dts/sun*dts >> and http://linux-sunxi.org/SATA#Devices_with_SATA_ports >> See also http://linux-sunxi.org/Category:Devices_with_SATA_port >> >> Patch v2: >> - Commented the patch in-place in ahci_sunxi.c >> - With bs=12K and no conv=... passed to dd, the write performance >> rises further to 132 MiB/s >> - Changed MB/s to MiB/s >> - Posted the story behind the patch: >> http://lkml.iu.edu/hypermail/linux/kernel/1905.1/03506.html >> - Posted a dd test script to find optimal bs, and some results: >> https://bit.ly/2YoOzEM >> >> Patch v1: >> - States bs=4K for dd and a write performance of 120 MiB/s >> >> Signed-off-by: Uenal Mutlu > > Acked-by: Maxime Ripard Thx! > Just a minor nitpick though, the part starting with RFC: and with the > version changelog should be after the --- below so that it doesn't get > applied as part of the commit log. Ok, I'll do it better in the future. Thx again. > Maxime > > -- > Maxime Ripard, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com