Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755958Ab2F1RxV (ORCPT ); Thu, 28 Jun 2012 13:53:21 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:42715 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755245Ab2F1RxT (ORCPT ); Thu, 28 Jun 2012 13:53:19 -0400 Date: Thu, 28 Jun 2012 20:53:03 +0300 From: Shmulik Ladkani To: Artem Bityutskiy Cc: Richard Genoud , linux-mtd@lists.infradead.org, David Woodhouse , linux-kernel@vger.kernel.org Subject: Re: [PATCH] UBI: add minimal amount of reserved erase blocks in Kconfig Message-ID: <20120628205303.676fa2ea@halley> In-Reply-To: <1340636918-7505-1-git-send-email-richard.genoud@gmail.com> References: <1340636918-7505-1-git-send-email-richard.genoud@gmail.com> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1341 Lines: 31 On Mon, 25 Jun 2012 17:08:38 +0200 Richard Genoud wrote: > diff --git a/drivers/mtd/ubi/misc.c b/drivers/mtd/ubi/misc.c > index f6a7d7a..c2c6db0 100644 > --- a/drivers/mtd/ubi/misc.c > +++ b/drivers/mtd/ubi/misc.c > @@ -100,8 +100,9 @@ void ubi_calculate_reserved(struct ubi_device *ubi) > { > ubi->beb_rsvd_level = ubi->good_peb_count/100; > ubi->beb_rsvd_level *= CONFIG_MTD_UBI_BEB_RESERVE; BTW Artem, I've always had an unresolved issue with this original calculation... maybe you can shed some light here. Why 'beb_rsvd_level' is set to RESERVE percent of the 'good_peb_count'? As the device gets worn, number of 'good_peb_count' will lessen over time - and as such, the 'beb_rsvd_level' may vary (lessen) over time. I'd expect a fixed number of 'beb_rsvd_level' PEBs for a given mtd partition, or more correctly, as Richard suggests, the *sum* of bad PEBs plus the beb reserved PEBs should be constant for a partition - as I do not expect more than a known constant of blocks to go bad during device's (and thus, partition's) lifetime. Regards, Shmulik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/