X-Spam-Check-By: sourceware.org Message-ID: <45955290.9090906@byu.net> Date: Fri, 29 Dec 2006 10:38:24 -0700 From: Eric Blake User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.9) Gecko/20061207 Thunderbird/1.5.0.9 Mnenhy/0.7.4.666 MIME-Version: 1.0 To: cygwin@cygwin.com Subject: Re: cp vs native copy performance; suboptimal st_blksize? References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 According to Brian Ford on 12/28/2006 2:15 PM: > > Current cp gets its initial buffer size from the st_blksize field > returned by fstat, which is currently set to 1k. I have found several > references on the web that state 64k is the "native" I/O size for the > disk cache manager. This might also fix the infamous USB transfer > rate issue as discussed here: > > http://www.cygwin.com/ml/cygwin/2006-08/msg00090.html > > Should we change st_blksize to 64k for performance reasons? > The benefit is non-trivial, IMHO. There is also the question of whether using posix_fallocate and posix_fadvise will help matters; it is something I've been meaning to get to, but as it currently depends on 1.7.x snapshots, it hasn't been my highest priority. - -- Don't work too hard, make some time for fun as well! Eric Blake ebb9@byu.net -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (Cygwin) Comment: Public key at home.comcast.net/~ericblake/eblake.gpg Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFlVKP84KuGfSFAYARArQDAKCjUYJOkLnQNZlG9JkoYwoAPtE6UQCZAUBo wOkuVDdl3ufT/DgjfKGtmio= =iYGO -----END PGP SIGNATURE----- -- 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/