Re: [PATCH v4 01/11] block: make generic_make_request handle arbitrarily sized bios

[Alasdair G Kergon]

On Tue, May 26, 2015 at 08:02:08AM -0700, Ming Lin wrote:
> Now bio_add_page() can build lager bios.
> And blk_queue_split() can split the bios in ->make_request() if needed.

But why not try to make the bio the right size in the first place so you
don't have to incur the performance impact of splitting?

What performance testing have you yet done to demonstrate the *actual* impact
of this patchset in situations where merge_bvec_fn is currently a net benefit?

Alasdair

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