On Mon, May 25, 2009 at 09:46:47AM +0200, Jens Axboe wrote: > > But that patch looks good to me, avoiding one allocation for each > > command and simplifying the code. I try to remember why these were > > two slabs to start with but can't find any reason. > > > > Btw, we might just want to declare the sense buffer directly as a sized > > array in the scsi command as there really doesn't seem to be a reason > > not to allocate it. > > That is also a workable solution. I've been trying to cut down on the > number of allocations required per-IO, and there's definitely still some > low hanging fruit there. Some of it is already included, like the inline > io_vecs in the bio. Btw, one thing I wanted to do for years is to add ->alloc_cmnd and ->destroy_cmnd method to the host template which optionally move the command allocation to the LLDD. That way we can embedd the scsi_cmnd into the drivers per-commad structure and eliminate another memory allocation. Also this would naturally extend the keep one cmnd pool to drivers without requiring additional code. As a second step it would also allow killing the scsi_host_cmd_pool byt just having a set of library routines that drivers which need SLAB_CACHE_DMA can use. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
