From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom.Wang Date: Sat, 12 Jul 2008 11:37:44 -0400 Subject: [Lustre-devel] Vector I/O api In-Reply-To: References: Message-ID: <4878CFC8.3040203@sun.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org Peter Braam wrote: > Tom - > > In a recent call with CERN the request came up to construct a call > that can in parallel transfer an array of extents in a single file to > a list of buffers and vice-versa. > This call should be executed with read-ahead disabled, it will usually > be made when the user is well informed of the I/O that is about to > take place. > Is this easy to get into the Lustre client (using our I/O library)? > Do you have this already for MPI/IO use? > > Thanks. > > Peter Hello, Peter If you mean provide this list buffer read/write API in MPI by our library, it is easy. Because MPI already provide such API, you can define proper discontingous buf_type and file_type of these extents, and use (MPI_File_Write/read_all) to read/write these buffers in one call . We only need disable read-ahead here. So it should be easy to get into our I/O library. But if you mean provide such API in llite, I am not sure it is easy. because it seems we could only use ioctl to implement such non-posix API IMHO, which always has page-size limit for transferring buffers here? It is probably I misunderstand something here. Thanks WangDi > This kind of list buffers transferring can be implemented with proper MPI file_view > ------------------------------------------------------------------------ > > _______________________________________________ > Lustre-devel mailing list > Lustre-devel at lists.lustre.org > http://lists.lustre.org/mailman/listinfo/lustre-devel > -- Regards, Tom Wangdi -- Sun Lustre Group System Software Engineer http://www.sun.com