On Sun, 23 Oct 2005, Jeff Garzik wrote: > Douglas Gilbert wrote: > > Which in turn makes me think of applying the same idea > > to max_sectors > > > > shost->max_sectors = MAX_512B_SECTORS_UNLIMITED; > > > Won't work. max_sectors is communicated to the block layer, where we limit > the overall size of the request for practical reasons. > > Read the comment in libata-scsi's slave_configure: > > /* TODO: 1024 is an arbitrary number, not the > * hardware maximum. This should be increased to > * 65534 when Jens Axboe's patch for dynamically > * determining max_sectors is merged. > */ > > Right now, setting the true hardware / command set maximum would use way too > much memory, with no way to get feedback from the VM. > > This is why SCSI_DEFAULT_MAX_SECTORS is defined to 1024. > So, the block layer is just for devices using the page cache, after all! If max_sectors is a VM thing, why is it set by _device drivers_? Now, let me try to more be constructive. max_sectors is enforced in __bio_add_page(). Maybe this is not the correct place. Bios are advocated as general i/o concepts and they don't have any direct relation with VM. -- 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
