From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Pringlemeir Date: Thu, 02 Apr 2015 16:30:43 -0400 Subject: [U-Boot] [PATCH 1/2] mtd: vf610_nfc: remove caching of page in buffer In-Reply-To: <1427965511-30658-1-git-send-email-stefan@agner.ch> (Stefan Agner's message of "Thu, 2 Apr 2015 11:05:10 +0200") References: <1427965511-30658-1-git-send-email-stefan@agner.ch> Message-ID: <87twwyl1cc.fsf@nbsps.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 2 Apr 2015, stefan at agner.ch wrote: > To improve performance we remember the current page in the buffer > and avoid reading it twice. This implicit page cache increases > complexity while does not increase performance in real world cases. > This patch removes that feature. > --- > As discussed in the other patchset... > http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/215802 > ...I did some performance measurements: > Time to "Starting kernel ..." > - without bad block scan & with UBIFS fastmap: 2.02s > - with bad block scan & with UBIFS fastmap: 3.99s > - without bad block scan & without UBIFS fastmap: 4.42s > - with bad block scan & without UBIFS fastmap: 6.38s > Without page cache (with this patch applied): > Time to "Starting kernel ..." > - without bad block scan & with UBIFS fastmap: 2.02s > - with bad block scan & with UBIFS fastmap: 4.01s > - without bad block scan & without UBIFS fastmap: 4.41s > - with bad block scan & without UBIFS fastmap: 6.39s [snip] I also measured 'write performance' with the mtd_speedtest (performing similar patch to the Linux driver) and I see no difference. I think a write benchmark is more appropriate to test this functionality? While at least it seems that neither read nor write is affected by the simplification. Fwiw, Bill Pringlemeir.