From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Braam Date: Thu, 21 Aug 2008 23:02:30 -0600 Subject: [Lustre-devel] Readx issue In-Reply-To: <48AE46F0.9060105@sun.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org Very exciting. I have cc'd lustre-devel, because this is exciting. Peter On 8/21/08 10:56 PM, "Tom.Wang" wrote: > Hello, > > Readx/writex code has been done based on HEAD. (ACC-sm has been passed) > > Since the target here is to issue the vector read extents req parallel, > so I chosed to implement that by read-ahead > group io, which is async and parallel. And also by this way, it will not > touch other module of lustre. > > In vector read-ahead, each read request will control their read-ahead by > itself, instead of by the current read-ahead window, where multi > read-threads(for the same file) use single read ahead window. > > Because current read-ahead > 1)Use a single continuous RA window to control the read ahead. > 2)The read-ahead moves forward according to the global RA window(for > all the read threads of this file), so it tries to favour all the read > threads of the file, > > This algorithm is not very nice for vector read-ahead. because > 1) It is hard to manage the multi discontinuous read-ahead window, for > example add/remove the extents from the window will be very subtle. > 2) It is hard to favour all the vector read-threads(for the file) by 1 > single read-ahead window. > > So I let each vector read threads control their read-ahead themselves, > which will make implementation very easy, and it will also not touch > original read-ahead algorithm for non-vector read. If you disagree > about this, please tell me. > > So all the implementation(readx,writex) actually did not touch other > module at all currently. I will ask some senior ppl to inspect the > patch. I do not know the further plan with CERN, will they try this > current release or HEAD? If they want try it in current release. Is that > ok I could land it in b1_6 or b1_8 after it pass inspection? Please advise. > > Thanks > WangDi