On Mon, 2006-06-19 at 15:32 +0800, Qingqing Zhou wrote: > "ITAGAKI Takahiro" <[EMAIL PROTECTED]> wrote > > > > > > I'm interested in it, with which we could improve responsiveness during > > checkpoints. Though it is Linux specific system call, but we could use > > the combination of mmap() and msync() instead of it; I mean we can use > > mmap only to flush dirty pages, not to read or write pages. > > > > Can you specify details? As the TODO item inidcates, if we mmap data file, a > serious problem is that we don't know when the data pages hit the disks -- > so that we may voilate the WAL rule.
Can't see where we'd use it. We fsync the xlog at transaction commit, so only the leading edge needs to be synced - would the call help there? Presumably the OS can already locate all blocks associated with a particular file fairly quickly without doing a full cache scan. Other files are fsynced at checkpoint - always all dirty blocks in the whole file. -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
