From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Xin Zhao" Subject: Why will NFS client spend so much time on file open? Date: Thu, 24 Aug 2006 03:15:38 -0400 Message-ID: <4ae3c140608240015v6078fc29r287601aad7a2f1dc@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: To: linux-kernel , linux-fsdevel@vger.kernel.org Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Hi, I did Apache benchmark and collected the performance results at the file system call level. The microbenchmark results were collected when I did "make" on Apache source code. The results are very interesting: open read Total Time (s) 21.599 15.948 Count 310274 98028 Time/Call (ms) 69.61 162.69 The results show that NFS spent even more time on file open than on file read. But this result confuses me: what does NFS do to open a file? As far as I know, it just issues a lookup() RPC to get file handle, and maybe a getattr() RPC to get file attributes. This should not take so much time. Can someone explain why this could happen? Thanks, -x