Messages in this thread | | | Date | Thu, 10 Jan 2002 11:34:22 +0100 | From | Andrea Arcangeli <> | Subject | Re: [PATCH] PAGE_SIZE IO for RAW (RAW VARY) |
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On Wed, Jan 09, 2002 at 03:48:17PM -0800, Badari Pulavarty wrote: > Alan, > > > > > > If it is not reasonable to fix all the brokern drivers, > > > how about making this configurable (to do variable size IO) ? > > > Do you favour this solution ? > > > > We have hardware that requires aligned power of two for writes (ie 4K on > > 4K boundaries only). The 3ware is one example Jeff Merkey found > > > > emm.. come to think of it, I can easily (2 line) change my patch to > do 512 byte buffer heads till we get PAGE alignment and then start > issuing 4K IO buffer heads. What do you think ? will this work ?
you should make sure the buffer is naturally aligned with the b_size (so you emulate the change of blocksize in a filesystem), if it wasn't the case you should fix it.
> > And also, do you know any low level drivers Ben mentioning: > > > low level drivers, some of which assume that > > all buffer heads within a request have the same block size. > > Is it still true for 2.4 ?
yes, you simply need to call submit_bh or to use separate ll_rw_blocks when you change b_size.
> > Regards, > Badari
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