At 11:37 AM 4/12/2004, you wrote: >Hi, > I have some questions about handling of sparse file in cygwin 1.5.5 >onwards. cygwin makes a file as a sparse if there is a write request >beyond 128 KB from file end. I am not sure whether it is a heuristic or >some statistical fact governs the use of 128 KB. Please clarify.
<http://www.google.com/search?as_q=&num=10&hl=en&ie=UTF-8&oe=UTF-8&btnG=Google+Search&as_epq=sparse+file&as_oq=&as_eq=&lr=&as_ft=i&as_filetype=&as_qdr=all&as_nlo=&as_nhi=&as_occt=any&as_dt=i&as_sitesearch=cygwin.com&safe=images> >The code of fhandler_base::write in fhandler.cc suggest that the check for >sparse file runs if there has been a seek before write request. The code >performs fine when dealing with local file. For files on network (netapps >or samba) write performance degrades because of this code. If a testcase >performs seek followed by write then each time code checks whether the >file is sparse or not. In that case GetFileSize gets called each time >write is performed, which takes good amount of time on network. >Is there any alternative to GetFileSize which >does not take much time? I searched in MSDN and found none faster than >GetFileSize. I can't speak to that. I suppose one option is to just conditionalize sparse files to local drives. Others may have better ideas though. -- Larry Hall http://www.rfk.com RFK Partners, Inc. (508) 893-9779 - RFK Office 838 Washington Street (508) 893-9889 - FAX Holliston, MA 01746 -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
