On 02/07/2013 02:29 PM, Bart Van Assche wrote: > On 02/07/13 13:08, Boaz Harrosh wrote: >> (My addition is for support of sg_lists to bsg, in a way that makes Tomo >> happy >> I know that qemu was wanting this for a while as well as the multitude of >> user-mode servers) > > Do you think it would help / make sense if sg_alloc_table() would be > modified such that it allocates the entire scatterlist table via one > vmalloc() call instead of chaining several page-sized scatterlist tables > ? Note: such a change is not possible without modifying > scsi_alloc_sgtable(). >
I don't think so, no. sg_alloc_table() is used not only for direct IO also for buffered, Now vmalloc() is terribly slow and would be a bottleneck in today's SSD performance. I love it that the Linux Kernel never uses vmalloc internally, and only ever chains everything to upto PAGE_SIZE sized objects. Coming from all these other OSs that don't, believe me, it is great great performance pain. (TLBs are a bitch) > Bart. > Thanks Boaz -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
