From mboxrd@z Thu Jan 1 00:00:00 1970 From: Parav Pandit Subject: returning scsi I/O to OS from interrupt handler Date: Sun, 26 Aug 2007 09:11:38 -0700 (PDT) Message-ID: <474470.84138.qm@web30115.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Received: from web30115.mail.mud.yahoo.com ([209.191.69.47]:46477 "HELO web30115.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752835AbXHZQLj (ORCPT ); Sun, 26 Aug 2007 12:11:39 -0400 Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org Hi, A low level SCSI HBA driver can return the I/O back to the OS from various paths. Some of the common possible paths 1, enqueue_command itself 2. Timer handler (at the time of command timeout) 3. Interrupt handler (when a response is received from the storage) 4. DPC handler thread. Whenever an I/O is returned from the interrupt handler by invoking scsi_done callback function, it will invoke the SCSI mid layer. 1. Is it good practice to return call scsi_done callback function from Interrupt handler? If no, may I know the implications of doing that? (other then blocking the interrupt context for a longer time) 2. if multiple I/Os are returned in a single interrupt, how many commands should be returned by calling scsi_done before shifting to dpc thread? Regards, Parav Pandit ____________________________________________________________________________________ Got a little couch potato? Check out fun summer activities for kids. http://search.yahoo.com/search?fr=oni_on_mail&p=summer+activities+for+kids&cs=bz