From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Evers Subject: Re: [PATCH RFC] increase ST_MAX_TAPES from 128 to 1024 Date: Fri, 17 Aug 2012 16:57:49 -0400 Message-ID: <502EB04D.2000007@redhat.com> References: <1345215024-5883-1-git-send-email-revers@redhat.com> <1345217873.2838.12.camel@dabdike.int.hansenpartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:7182 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753657Ab2HQU6C (ORCPT ); Fri, 17 Aug 2012 16:58:02 -0400 In-Reply-To: <1345217873.2838.12.camel@dabdike.int.hansenpartnership.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Kai.Makisara@kolumbus.fi, jeffm@suse.com, lduncan@suse.com, linux-scsi@vger.kernel.org On 08/17/2012 11:37 AM, James Bottomley wrote: > On Fri, 2012-08-17 at 10:50 -0400, Rob Evers wrote: >> Wondering if this would be an acceptable interim solution >> to increasing the limit on the number of tape drives >> while http://marc.info/?l=linux-scsi&m=134212042809524&w=2 >> gets sorted out. >> >> Signed-off-by: Rob Evers >> --- >> drivers/scsi/st.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/scsi/st.h b/drivers/scsi/st.h >> index b548923..408d24f 100644 >> --- a/drivers/scsi/st.h >> +++ b/drivers/scsi/st.h >> @@ -76,7 +76,7 @@ struct st_modedef { >> #define ST_MODE_SHIFT (7 - ST_NBR_MODE_BITS) >> #define ST_MODE_MASK ((ST_NBR_MODES - 1)<< ST_MODE_SHIFT) >> >> -#define ST_MAX_TAPES 128 >> +#define ST_MAX_TAPES 1024 > This is going to cause an order 2 GFP_ATOMIC allocation (on 64 bit > platforms) for the contiguous scsi_tapes array ... if large numbers of > tapes are genuinely required, shouldn't we fix this first and then > expand the number quite a bit more? > > James > Pre allocation of cdevs during init time needs addressing as well to increase ST_MAX_TAPES quite a bit more, right? Would leaving out Lee's sysfs updates out be ok, if ST_MAX_TAPES were significantly increased? Rob