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Sat, 15 Apr 2023 04:00:37 +0200 Date: Sat, 15 Apr 2023 04:00:33 +0200 From: Jonathan =?utf-8?Q?Neusch=C3=A4fer?= To: Arnd Bergmann Cc: Jonathan =?utf-8?Q?Neusch=C3=A4fer?= , linux-arm-kernel@lists.infradead.org, Russell King , Nick Terrell , Tony Lindgren , Geert Uytterhoeven , Linus Walleij , Sebastian Reichel , "Hawkins, Nick" , Christophe Leroy , Florian Fainelli , Nick Desaulniers , Xin Li , Seung-Woo Kim , Paul Bolle , Bart Van Assche , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/3] ARM ZSTD boot compression Message-ID: References: <20230412212126.3966502-1-j.neuschaefer@gmx.net> <9ae523ae-aad4-40b1-8b6b-d5e18bf8b92a@app.fastmail.com> MIME-Version: 1.0 In-Reply-To: X-Provags-ID: V03:K1:dM6Pk1H8/3BPe+XLgtnk5l30A5hDSGMhXcW4Baf8aIZBbz1Q5Lj gijykOFKwz9kAkn5OGnh8S0uPrpIv9hy0mlwr7GQ7bLVzP9SL0NE9knZyt/eXJDuu2sFjEB 5pCUv2Hq1J16EqqzrQ7aOoZIrvL8Bz0tS4EkYjBI40t5H088blsLIMIeh8W/BVxiNuB0+Ok P7RUU/wVxULGhH51boavQ== UI-OutboundReport: notjunk:1;M01:P0:5T46tHmqSH0=;8aLgwAkeX0DLCn04ncyL4b0nqUJ CmeouTgLEk8A964S8R6xrM9vKibBFJ52+olRxLPfvRRA2udb67oAbTnfjTjjEv3ZkhGpES7+O oSC4ybRqx7c+/4GorI8u45UKTXFeVzDM45EqR7lOqYcdSiGpLJkNd4eJOC6PNyM9B4e4LVUNS 2TPKL34ZFPg58EZT9R1/27fMvlV0iVoUG1BDLrGL12bpo7Xjs8p1wAaPCdJRdcej1hgnFdGjw 5v709vvZUu0VoZmP+3JeD0t1KMtf+T/CwdH9kPbQDI3HZnmPZfYb3VEmw1RmKPpXoWjM+H3Xv gg+/ubN5MCyzozpyBQbUYlfga5BVId6iUmS1G1xdx41LZ7sRPPWuR236dE5IcaijUxH67311r Fa+bhH5jHSdR68gYGy/2oi53iwFOqBAAI0iUvbwH0V3D99PjzC8OAqDk56iw1ExteJj/XbofQ IAwZMx/r97+lTLCmCNWh9KUZlTOiCXbklFTNpNwtG1H7L18nFI8SeJJe2JtWzr2DntBKNh70I ea1eLQND/d6lQ2sN2hohAunPwS19LnMM5jUHP1j6Ey3vWtnUaXRXnecK4FFGvkQr9u4GFRdCI 1HmkAywsDe9CB+ScpJSTiecsGnxaqz4ilaQKDdKOOa9Yi57JEQn+yBaVRY9wghxLwl5XyFfff QJZBImdWhNmcbK12Yd6FvXuqnq6kHUuVAcgjDA/cubGFsf6A4yvoqgeTUvCyM0v1MOd7P+sC8 LnDgyWEI6zhgjIU59rl31TACk6We0R5DrSiLi22C+WYGTUICgZ0DUYDFaS+r7r5OgjOw2uytI yiFuG8tnhQ24BvCl5qHqr9phKf/RpjYTcjWQh+/gCAZbc/UpJn4RYaDZV0o5zP9ormxSt3PkI /NheVePPDWjwGEYTdkwPmAOKK2lzfjnBIoN6PeR1AGR0ZTbzK7GY3mn6h/0+DRptvc0GjBEB8 r3Njej1skLqOwmyRARfuESmJXBg= X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230414_190121_118061_8AEA23BD X-CRM114-Status: GOOD ( 24.28 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============5726814003621758415==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============5726814003621758415== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="tUChAbDuev3sy1VC" Content-Disposition: inline --tUChAbDuev3sy1VC Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Apr 13, 2023 at 01:13:21PM +0200, Arnd Bergmann wrote: > On Wed, Apr 12, 2023, at 23:33, Arnd Bergmann wrote: > > On Wed, Apr 12, 2023, at 23:21, Jonathan Neusch=C3=A4fer wrote: > >> This patchset enables ZSTD kernel (de)compression on 32-bit ARM. > >> Unfortunately, it is much slower than I hoped (tested on ARM926EJ-S): > >> > >> - LZO: 7.2 MiB, 6 seconds > >> - ZSTD: 5.6 MiB, 60 seconds > > > > That seems unexpected, as the usual numbers say it's about 25% > > slower than LZO. Do you have an idea why it is so much slower > > here? How long does it take to decompress the > > generated arch/arm/boot/Image file in user space on the same > > hardware using lzop and zstd? >=20 > I looked through this a bit more and found two interesting points: >=20 > - zstd uses a lot more unaligned loads and stores while > decompressing. On armv5 those turn into individual byte > accesses, while the others can likely use word-aligned > accesses. This could make a huge difference if caches are > disabled during the decompression. >=20 > - The sliding window on zstd is much larger, with the kernel > using an 8MB window (zstd=3D23), compared to the normal 32kb > for deflate (couldn't find the default for lzo), so on > machines with no L2 cache, it is much likely to thrash a > small L1 dcache that are used on most arm9. >=20 > Arnd Make sense. For ZSTD as used in kernel decompression (the zstd22 configuration), the window is even bigger, 128 MiB. (AFAIU) Thanks Jonathan --tUChAbDuev3sy1VC Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEvHAHGBBjQPVy+qvDCDBEmo7zX9sFAmQ6BUEACgkQCDBEmo7z X9tlOA//SDYTuVEU43pN9k/3lyWTymKfJ7d9WXttxT9YJ+pIeNougz1W0HipefGr sfmBu4Z47iRaJYPAUDXGo28UFXUgAHxPmJ0CbPOpOkdV11IdB545eT63t9xajH7Q yUF3CH3gPU2wKX9stnD+i5B5UuoY5cK+AproPBoMmADR3hTepama8DsFwXmGrsuT e39oUsp/7G0l8rWfRJ0y+CWQIXDJWXattL/kIofVZXTSxKbj+zntzqVDKjgZDVcZ 3BNUWi3BSDFiHrULQAY2KKBCxK4RN/av0SwCKb6E2q5iqxenLw4y/aCQImjrx7Y3 Tf8lLAnPwmRI8acWIVuCU86JXAO6XR8Z8/ciDJ6apWaHhYQDm6VGw4dp5/M9f2KL XOXne4jGfPHamLORYx4Gg+5z3mxqORTO2SsJdjN1fp7uDg/QcA7CEhucx0e0V/2e fE66F7BlqCBBv+rlStoaBaJE2VPLhslpZGJN/htI/8kkItQxvGJlYXdeJpreuMZA fB4XNk9pacFx/m6RfvDxLQRvuKQTP0uWgRsbVCix4C7BZKR2yPhB1jPedZ/kROGY ptDqwJmEQxhxnTvdvbsrXgebltx8a7zNmcVERYWCRaElgvDv1PmPX7DoAqTnWRC+ de3ra8/aJJcWIjHrGKpBNaAsO86+TVr+p8vC/xGbEiC7/F36QEQ= =uukq -----END PGP SIGNATURE----- --tUChAbDuev3sy1VC-- --===============5726814003621758415== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============5726814003621758415==--