Date: Fri, 11 Mar 2005 16:55:25 +0300 From: dima <_pppp@mail.ru> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: ru@FreeBSD.org Subject: Re[2]: Giant-free polling [PATCH] Message-ID: <E1D9kbt-000FAj-00._pppp-mail-ru@f22.mail.ru> In-Reply-To: <20050311110234.GA87255@cell.sick.ru>
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------T4Mc1hoV-B6SDJqxFbvhAdRDo:1110549325 Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 8bit > Collegues, > > On Tue, Mar 01, 2005 at 04:29:49PM -0800, Luigi Rizzo wrote: > L> [cc-ing net@freebsd.org to get more opinions] > > this good, that you have CC'ed net@, otherwise we would continue > working in parallel without collaboration. It's a pity you didn't read the complete thread, thus the original version of my patch isn't valid anymore. > > Here is attached patch made in a collaboration by ru, pjd and me. I thought about using list also, but considered it to bring too much overhead to the code. The original idea of handling arrays seems to be very elegant. > > We use separate mutex for polling, and we drop it before calling the > poll handler to avoid LOR and contention on this mutex. The recent version of the patch uses sx lock to protect pr[] and the array of per-interface mutexes iface_locks[]. So, all CPUs can poll different interfaces at the same time now. See the complete thread for details. > > We have definite evidence that now idle_poll and ISR poll can run > in parallel: if we remove PRF_RUNNING flag check, we got panics > because poll handlers of many drivers (e.g. if_em) are not reentrable. > > I think this patch is a step forward in direction of parallel polling > on SMP, since we now have two polling instances (ISR + idle) working > in parallel. I also mentioned that poll_idle() isn't called from anywhere in the kernel. Thus we have only 2 possible sources for polling: hardclock (per-CPU) and traps. The polling code in trap handler should also be changed a bit to check for the trap's source. I attach the most recent version of the patch. The only difference is locking in ether_poll_register() suggested by Luigi. > > -- > Totus tuus, Glebius. > GLEBIUS-RIPN GLEB-RIPE ------T4Mc1hoV-B6SDJqxFbvhAdRDo:1110549325 Content-Type: application/octet-stream; name="kern_poll.patch" Content-Disposition: attachment; filename="kern_poll.patch" Content-Transfer-Encoding: base64 LS0tIG9yaWcva2Vybl9wb2xsLmMJVGh1IEZlYiAxNyAxNzoxMTowNSAyMDA1CisrKyBrZXJuX3Bv bGwuYwlGcmkgTWFyICA0IDE3OjAzOjMzIDIwMDUKQEAgLTQxLDEyICs0MSwxNyBAQAogI2luY2x1 ZGUgPHN5cy9yZXNvdXJjZXZhci5oPgogI2luY2x1ZGUgPHN5cy9rdGhyZWFkLmg+CiAKKyNpbmNs dWRlIDxzeXMvbG9jay5oPgkJCS8qIGZvciBzeCg5KQkJCSovCisjaW5jbHVkZSA8c3lzL3N4Lmg+ CisKICNpZmRlZiBTTVAKICNpZm5kZWYgQ09NUElMSU5HX0xJTlQKICNlcnJvciBERVZJQ0VfUE9M TElORyBpcyBub3QgY29tcGF0aWJsZSB3aXRoIFNNUAogI2VuZGlmCiAjZW5kaWYKIAorc3RydWN0 IHN4IHBvbGxpbmdfbG9jazsKKwogc3RhdGljIHZvaWQgbmV0aXNyX3BvbGwodm9pZCk7CQkvKiB0 aGUgdHdvIG5ldGlzciBoYW5kbGVycyAgICAgICovCiBzdGF0aWMgdm9pZCBuZXRpc3JfcG9sbG1v 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