From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xavier Bru Date: Fri, 13 May 2005 17:34:46 +0000 Subject: Re: CONFIG_FORCE_MAX_ZONEORDER default value Message-Id: <4284E536.3090107@bull.net> MIME-Version: 1 Content-Type: multipart/mixed; boundary="------------000107030004030400070903" List-Id: References: <200505040850.CAA10967@udlkern.fc.hp.com> In-Reply-To: <200505040850.CAA10967@udlkern.fc.hp.com> To: linux-ia64@vger.kernel.org This is a multi-part message in MIME format. --------------000107030004030400070903 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8"; format="flowed" Hi John & all We also have a concern about CONFIG_FORCE_MAX_ZONEORDER=18 default value with 64k page size, we get the message: "BUG: wrong zone alignment, it will crash" This is due to the normal zone (4 GB) not being aligned on the maximum order boundary (8GB). A possible fix for this problem is to set the value to 17 for 64k pages... linux-2.6.11-kgdb/arch/ia64/Kconfig --- linux-2.6.11r/arch/ia64/Kconfig 2005-05-11 15:23:34.000000000 +0200 +++ linux-2.6.11/arch/ia64/Kconfig 2005-05-13 17:55:56.072557343 +0200 @@ -229,6 +229,7 @@ config IA64_SGI_SN_SIM config FORCE_MAX_ZONEORDER int + default "17" if IA64_PAGE_SIZE_64KB default "18" config SMP John Marvin wrote: >I was wondering why CONFIG_FORCE_MAX_ZONEORDER was changed from 19 (in 2.4) >to 18 (in 2.6). Note that this value sets the maximum number of orders, >i.e. the actual maximum order is one less, i.e. 17. For the 16Kb default >page size this gives you a maximum page size of 2Gb, which isn't >particularly useful on ia64 since that size is not supported. The only >reason I can see 18 being useful would be to allow for 1Gb huge pages >on a system where PAGE_SIZE is set to 8Kb. > >Anyway, with the default page size being 16K, it seems that it would >be more appropriate for CONFIG_FORCE_MAX_ZONEORDER to be either 17 (for >a 1 Gb max huge page size) or 19 (to support the maximum 4 Gb page size >available on Itanium 2 systems). > >Is there another consideration that I've missed? > >John Marvin >- >To unsubscribe from this list: send the line "unsubscribe linux-ia64" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- Sincères salutations. --------------000107030004030400070903 Content-Transfer-Encoding: 8bit Content-Type: text/x-vcard; charset=utf-8; name="xavier.bru.vcf" Content-Disposition: attachment; filename="xavier.bru.vcf" begin:vcard fn:Xavier Bru n:Bru;Xavier adr:;;1 rue de Provence, BP 208;Echirolles;;38432 Cedex;France email;internet:Xavier.Bru@bull.net title:BULL/DT/Open Software/linux/ia64 tel;work:+33 (0)4 76 29 77 45 tel;fax:+33 (0)4 76 29 77 70 x-mozilla-html:TRUE url:http://www-frec.bull.fr version:2.1 end:vcard --------------000107030004030400070903--