majianpeng <majianp...@gmail.com> writes: > On 2012-07-27 22:21 Jeff Moyer <jmo...@redhat.com> Wrote: >>majianpeng <majianp...@gmail.com> writes: >> >>> When exec bio_alloc, the bi_rw is zero.But after calling bio_add_page, >>> it will use bi_rw. >>> Fox example, in functiion __bio_add_page,it will call merge_bvec_fn(). >>> The merge_bvec_fn of raid456 will use the bi_rw to judge the merge. >>>>> if ((bvm->bi_rw & 1) == WRITE) >>>>> return biovec->bv_len; /* always allow writes to be mergeable */ >>> >>> Signed-off-by: Jianpeng Ma <majianp...@gmail.com> >> >>Good catch. How did you find this? Did you experience data corruption >>as a result of this oversight, reduced performance due to missed merge >>opportunities, or did you just notice it in reviewing the code? >> >>Reviewed-by: Jeff Moyer <jmo...@redhat.com> >> > Sorry for late to reply. When i analysed the performance of raid5, i found > this bug.
OK, thanks. In the future, it would be good to include that information in the patch description. Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
