On Wed, 1 Mar 2006, Jens Axboe wrote: > On Tue, Feb 28 2006, Kai Makisara wrote: > > This patch enables clustering and sets max_sectors to 0xffff to enable > > reading and writing of large blocks with tapes (and large transfers with > > sg). This change is needed after the sg and st drivers started using > > chained bios through scsi_request_async() in 2.6.16. > > > > Signed-off-by: Kai Makisara <kai.makisara@xxxxxxxxxxx> > > > > --- linux-2.6.16-rc5/drivers/scsi/sym53c8xx_2/sym_glue.c 2006-02-04 13:25:48.000000000 +0200 > > +++ linux-2.6.16-rc5-k1/drivers/scsi/sym53c8xx_2/sym_glue.c 2006-02-18 09:45:24.000000000 +0200 > > @@ -1978,7 +1978,8 @@ static struct scsi_host_template sym2_te > > .eh_bus_reset_handler = sym53c8xx_eh_bus_reset_handler, > > .eh_host_reset_handler = sym53c8xx_eh_host_reset_handler, > > .this_id = 7, > > - .use_clustering = DISABLE_CLUSTERING, > > + .use_clustering = ENABLE_CLUSTERING, > > + .max_sectors = 0xFFFF, > > Strictly speaking, the clustering bit is unrelated. It is related. The number of scatter/gather segments in the SCSI HBAs is limited. In order to fit the large requests into these limits, the adjacent pages (that have been split to bios) have to be recombined. > I seem to recall > Gerard years ago talking about some sym chips that did not like > clustering, hence it was disabled. > Facts? -- Kai - : 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
