Messages in this thread | | | Subject | Re: [RFC][PATCH] Cross Memory Attach | From | Valdis.Kletnieks@vt ... | Date | Wed, 15 Sep 2010 12:07:11 -0400 |
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On Wed, 15 Sep 2010 10:48:55 +0930, Christopher Yeoh said:
> The basic idea behind cross memory attach is to allow MPI programs doing > intra-node communication to do a single copy of the message rather than > a double copy of the message via shared memory.
Interesting, and nice benchmark results. I have a question though:
> + /* Get the pages we're interested in */ > + pages_pinned = get_user_pages(task, task->mm, pa, > + nr_pages_to_copy, > + copy_to, 0, process_pages, NULL); > + > + if (pages_pinned != nr_pages_to_copy) > + goto end;
...
> +end: > + for (i = 0; i < pages_pinned; i++) { > + if (copy_to) > + set_page_dirty_lock(process_pages[i]); > + put_page(process_pages[i]); > + }
It looks to me like if get_user_pages() fails to pin *all* the pages, we treat the target pages as dirty even though we never actually touched them?
Maybe it should be 'if (copy_to && *bytes_copied)'? [unhandled content-type:application/pgp-signature] | |