James Bottomley wrote: > On Thu, 2007-05-17 at 11:49 +0300, Boaz Harrosh wrote: >> These are regular fs (ext3) requests during bootup. The machine will not >> boot. (Usually from the read ahead code) >> Don't believe me look at the second patch Over Tomo's cleanup. >> If I define SCSI_MAX_SG_SEGMENTS to 127 it will crash even when I >> did in code: >> blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS); >> I suppose someone is looking at a different definition. Or there is >> another call I need to do for this to work. > > It would really help us if you showed the actual code for what you did > and where ... if this is wrong, we have bigger problems that quibbling > about bidirectional slab sizes. The correct way to adjust this limit > artificially to 127 is: > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 1f5a07b..4a27841 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1576,7 +1576,7 @@ struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, > return NULL; > > blk_queue_max_hw_segments(q, shost->sg_tablesize); > - blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS); > + blk_queue_max_phys_segments(q, 127); > blk_queue_max_sectors(q, shost->max_sectors); > blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost)); > blk_queue_segment_boundary(q, shost->dma_boundary); > > (It doesn't alter the allocation pools or anything else, just limits the > max phys segments of the queue). The way to check that this limit is > being honoured is: > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 1f5a07b..ae42e4d 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1000,6 +1000,7 @@ static int scsi_init_io(struct scsi_cmnd *cmd) > * kmapping pages) > */ > cmd->use_sg = req->nr_phys_segments; > + WARN_ON(req->nr_phys_segments > 127); > > /* > * If sg table allocation fails, requeue request later. > > James > > Yes Tomo found it at ata_scsi_slave_config(). Attached below the way I fixed it. Now it works with 127. (By the way Tomo, a printk like you did in scsi_init_io and scsi_free_sgtable, 2 for every IO, or even 1 for every IO, will make a SCSI booting PC like mine almost un-usable. Think of printk going to log-file doing a printk...) diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index dd81fa7..de8c796 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -800,7 +800,9 @@ int ata_scsi_slave_config(struct scsi_device *sdev) ata_scsi_sdev_config(sdev); - blk_queue_max_phys_segments(sdev->request_queue, LIBATA_MAX_PRD); + if ( sdev->request_queue->max_phys_segments > LIBATA_MAX_PRD ) + blk_queue_max_phys_segments(sdev->request_queue, + LIBATA_MAX_PRD); sdev->manage_start_stop = 1; - 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
