From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Woodhouse To: Martin Egholm Nielsen In-Reply-To: References: <1121867130.12903.15.camel@localhost.localdomain> <1121869156.12903.19.camel@localhost.localdomain> <1121887042.20077.1.camel@localhost.localdomain> Content-Type: text/plain Date: Sat, 23 Jul 2005 11:07:18 -0400 Message-Id: <1122131239.12630.34.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Cc: linux-mtd@lists.infradead.org Subject: Re: JFFS2 garbage collector blocking for minutes after mount List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2005-07-22 at 16:47 +0200, Martin Egholm Nielsen wrote: > 47695 idled 384,63710 > 2997 nand_read_buf 62,43750 > 1122 nand_calculate_ecc 5,84380 > 677 __delay 33,85000 > 502 nand_do_read_ecc 0,26370 Right, so we're spending most of that time actually reading the flash. If you just read the entire flash device, how long does that take? (time dd if=/dev/mtd0 of=/dev/null) Artem's patch will improve things further by building up the fragtree from newest to oldest node instead of from oldest to newest as we currently do -- which actually means we don't need to check the CRC on the oldest nodes before they never get added to the tree; we don't actually need to read their data payload at all. In the longer term, Ferenc's summary patch would decrease the amount of reading from the flash even further. I keep meaning to go through that in detail and make it mergeable. -- dwmw2