Hi Jesper- > On Feb 9, 2021, at 5:31 AM, Jesper Dangaard Brouer <brouer@xxxxxxxxxx> wrote: > > On Mon, 8 Feb 2021 17:50:51 +0000 > Chuck Lever <chuck.lever@xxxxxxxxxx> wrote: > >> Sorry for resending. I misremembered the linux-mm address. >> >>> Begin forwarded message: >>> >>> [ please Cc: me, I'm not subscribed to linux-mm ] >>> >>> We've been discussing how NFSD can more efficiently refill its >>> receive buffers (currently alloc_page() in a loop; see >>> net/sunrpc/svc_xprt.c::svc_alloc_arg()). >>> > > It looks like you could also take advantage of bulk free in: > svc_free_res_pages() We started there. Those pages often have a non-zero reference count, so that call site didn't seem to be a candidate for a bulk free. > I would like to use the page bulk alloc API here: > https://github.com/torvalds/linux/blob/master/net/core/page_pool.c#L201-L209 > > >>> Neil Brown pointed me to this old thread: >>> >>> https://lore.kernel.org/lkml/20170109163518.6001-1-mgorman@xxxxxxxxxxxxxxxxxxx/ >>> >>> We see that many of the prerequisites are in v5.11-rc, but >>> alloc_page_bulk() is not. I tried forward-porting 4/4 in that >>> series, but enough internal APIs have changed since 2017 that >>> the patch does not come close to applying and compiling. > > I forgot that this was never merged. It is sad as Mel showed huge > improvement with his work. > >>> I'm wondering: >>> >>> a) is there a newer version of that work? >>> > > Mel, why was this work never merged upstream? > > >>> b) if not, does there exist a preferred API in 5.11 for bulk >>> page allocation? >>> >>> Many thanks for any guidance! > > I have a kernel module that micro-bench the API alloc_pages_bulk() here: > https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/mm/bench/page_bench04_bulk.c#L97 > > -- > Best regards, > Jesper Dangaard Brouer > MSc.CS, Principal Kernel Engineer at Red Hat > LinkedIn: http://www.linkedin.com/in/brouer > -- Chuck Lever
