Date: Thu, 5 Sep 1996 16:51:25 +0900 (KST) From: Heo Sung-Gwan <heo@cslsun10.sogang.ac.kr> To: freebsd-hackers@FreeBSD.ORG Subject: Questions about cluster read buffer cache Message-ID: <Pine.SUN.3.93.960905164903.19739A-100000@cslsun10>
next in thread | raw e-mail | index | archive | help
Hi, I have some questions about cluster read-ahead buffer cache. When a file is read sequentially, one cluster is always prefetched that is not requested yet. At least vp->v_ralen blocks are already in buffer. If the difference between the most recently accessed block and the most recently prefetched block is greater than vp->v_ralen, next cluster is read ahead into buffer. During reading a file sequentially the value of vp->v_ralen is 7. Why is it? And if the blocks in a cluster is requested before the completion of asynchronous read-ahead of the cluster, how is this situation handled? Which part of vfs_cluster.c does handle this? -- Heo Sung-Gwan O.S. Lab. Dept. of Computer Science, Sogang University, Seoul, Korea. E-mail: heo@oslab.sogang.ac.kr
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.SUN.3.93.960905164903.19739A-100000>