On 09/11/2014 11:02 AM, Kashyap Desai wrote: >> -----Original Message----- >> From: Vivek Goyal [mailto:vgoyal@xxxxxxxxxx] >> Sent: Wednesday, September 10, 2014 9:17 PM >> To: Tomas Henzl >> Cc: Elliott, Robert (Server Storage); Sumit Saxena; > linux-scsi@xxxxxxxxxxxxxxx; >> martin.petersen@xxxxxxxxxx; hch@xxxxxxxxxxxxx; >> jbottomley@xxxxxxxxxxxxx; Kashyap Desai; aradford@xxxxxxxxx; Michal >> Schmidt; amirv@xxxxxxxxxxxx; Jens Axboe <axboe@xxxxxxxxx> >> (axboe@xxxxxxxxx); scameron@xxxxxxxxxxxxxxxxxx >> Subject: Re: [PATCH 04/11] megaraid_sas : Firmware crash dump feature >> support >> >> On Wed, Sep 10, 2014 at 05:28:40PM +0200, Tomas Henzl wrote: >>> On 09/10/2014 05:06 PM, Elliott, Robert (Server Storage) wrote: >>>>> From: linux-scsi-owner@xxxxxxxxxxxxxxx [mailto:linux-scsi- >>>>> owner@xxxxxxxxxxxxxxx] On Behalf Of Sumit Saxena >>>>> >>>>>> From: Tomas Henzl [mailto:thenzl@xxxxxxxxxx] >>>>>> >>>>>> With several controllers in a system this may take a lot memory, >>>>>> could you also in case when a kdump kernel is running lower it, by >>>>>> not using this feature? >>>>>> >>>>> Agreed, we will disable this feature for kdump kernel by adding >>>>> "reset_devices" global varaiable. >>>>> That check is required for only one place, throughout the code, >>>>> this feature will remain disabled. Code snippet for the same- >>>>> >>>>> instance->crash_dump_drv_support = (!reset_devices) && >>>>> crashdump_enable && >>>>> instance->crash_dump_fw_support && >>>>> instance->crash_dump_buf); >>>>> if(instance->crash_dump_drv_support) { >>>>> printk(KERN_INFO "megaraid_sas: FW Crash dump is >>>>> supported\n"); >>>>> megasas_set_crash_dump_params(instance, >>>>> MR_CRASH_BUF_TURN_OFF); >>>>> >>>>> } else { >>>>> .. >>>>> } >>>> Network drivers have been running into similar problems. >>>> >>>> There's a new patch from Amir coming through net-next to make >>>> is_kdump_kernel() (in crash_dump.h) accessible to modules. >>>> That may be a better signal than reset_devices that the driver >>>> should use minimal resources. >>>> >>>> http://comments.gmane.org/gmane.linux.network/324737 >>>> >>>> I'm not sure about the logistics of a SCSI patch depending on a >>>> net-next patch. >>> Probably better to start with reset_devices and switch to >>> is_kdump_kernel() later. >>> This is not a discussion about reset_devices versus is_kdump_kernel, >>> but while it looks good to have it distinguished - is the >>> reset_devices actually used anywhere else than in kdump kernel? >> I think usage of reset_devices for lowering memory footprint of driver > is >> plain wrong. It tells driver to only reset the device as BIOS might not > have >> done it right or we skipped BIOS completely. >> >> Using is_kdump_kernel() is also not perfect either but atleast better > than >> reset_devices. > We will use is_kdump_kernel() not to enable this feature in Kdump kernel. OK, just keep in mind that the is_kdump_kernel() is not yet in mainline. > > MegaRaid Driver will not allocate Host memory (which is used to collect > complete FW crash image) until and unless associated FW is crashed/IO > timeout. This is new for the driver? A previous reply stated that the driver will allocate 1MB for each MR controller at the 'start of the day'. If I misunderstood it somehow then nothing is needed. > Driver do allocation only if required. Also, it will break the function > immediately after memory allocation is failed and operate on available > memory. > > To be on safer side, we can disable this feature in Kdump mode. > > ~ Kashyap >> Thanks >> Vivek > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
