On Tue, 6 Dec 2005 23:48:14 +0100 Oliver Neukum <[EMAIL PROTECTED]> wrote:
| Am Dienstag, 6. Dezember 2005 21:13 schrieb Eduardo Pereira Habkost: | > Anyway, I don't see yet why the atomic_t would make the code slower on | > non-smp. Is atomic_add_unless(v, 1, 1) supposed to be slower than | > 'if (!v) v = 1;' ? | | spin_lock() can be dropped on UP. atomic_XXX must either use an operation | on main memory, meaning less efficient code generation, or must disable | interrupts even on UP. Hmmm, I didn't know about the possibility to disable interrupts. In the OOPS thread: http://marc.theaimsgroup.com/?l=linux-usb-devel&m=113269682409774&w=2 *IIUC*, Greg told us that we could think about the possibility to drop the spin lock and use the semaphore instead, because URB writes are slow. We (me and Eduardo) didn't like it because we would be using the same lock for two different problems, so we suggested the atomic_t, and Greg agreed (IIRC). Isn't it right? Is the URB write so fast that switching to atomic_t doesn't pay-off? -- Luiz Fernando N. Capitulino ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
