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Groups > linux.kernel > #1281192 > unrolled thread
| Started by | David Miller <davem@davemloft.net> |
|---|---|
| First post | 2015-12-01 21:40 +0100 |
| Last post | 2015-12-03 09:20 +0100 |
| Articles | 3 — 3 participants |
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Re: [PATCH] Improve Atheros ethernet driver not to do order 4 GFP_ATOMIC allocation David Miller <davem@davemloft.net> - 2015-12-01 21:40 +0100
Re: [PATCH] Improve Atheros ethernet driver not to do order 4 GFP_ATOMIC allocation Pavel Machek <pavel@ucw.cz> - 2015-12-03 08:50 +0100
Re: [PATCH] Improve Atheros ethernet driver not to do order 4 GFP_ATOMIC allocation Michal Hocko <mhocko@kernel.org> - 2015-12-03 09:20 +0100
| From | David Miller <davem@davemloft.net> |
|---|---|
| Date | 2015-12-01 21:40 +0100 |
| Subject | Re: [PATCH] Improve Atheros ethernet driver not to do order 4 GFP_ATOMIC allocation |
| Message-ID | <qAZSq-622-19@gated-at.bofh.it> |
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| From | Pavel Machek <pavel@ucw.cz> |
|---|---|
| Date | 2015-12-03 08:50 +0100 |
| Message-ID | <qBwOl-1XG-9@gated-at.bofh.it> |
| In reply to | #1281192 |
On Wed 2015-12-02 22:43:31, Chris Snook wrote: > On Tue, Dec 1, 2015 at 12:35 PM David Miller <davem@davemloft.net> wrote: > > > From: Michal Hocko <mhocko@kernel.org> > > Date: Mon, 30 Nov 2015 14:21:29 +0100 > > > > > On Sat 28-11-15 15:51:13, Pavel Machek wrote: > > >> > > >> atl1c driver is doing order-4 allocation with GFP_ATOMIC > > >> priority. That often breaks networking after resume. Switch to > > >> GFP_KERNEL. Still not ideal, but should be significantly better. > > > > > > It is not clear why GFP_KERNEL can replace GFP_ATOMIC safely neither > > > from the changelog nor from the patch context. > > > > Earlier in the function we do a GFP_KERNEL kmalloc so: > > > > ¯\_(ツ)_/¯ > > > > It should be fine. > > > > AFAICT, the people who benefit from GFP_ATOMIC are the people running all > their storage over NFS/iSCSI who are suspending their machines while > they're so busy they don't have any clean order 4 pagecache to drop, and > want the machine to panic rather than hang. The people who benefit >from iSCSI on machine that suspends... is that a joke or complicated way of saying that noone benefits? And code uses... both GFP_ATOMIC and GFP_KERNEL so that both sides are equally unhappy? :-). Do you want to test the patch, update the subject line and send it to Davem, or should I do it? Do you see a way to split the allocation? Not even order 4 GFP_KERNEL allocation is a nice thing to do... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Michal Hocko <mhocko@kernel.org> |
|---|---|
| Date | 2015-12-03 09:20 +0100 |
| Message-ID | <qBxho-2o6-25@gated-at.bofh.it> |
| In reply to | #1281192 |
On Wed 02-12-15 22:43:31, Chris Snook wrote: > On Tue, Dec 1, 2015 at 12:35 PM David Miller <davem@davemloft.net> wrote: > > > From: Michal Hocko <mhocko@kernel.org> > > Date: Mon, 30 Nov 2015 14:21:29 +0100 > > > > > On Sat 28-11-15 15:51:13, Pavel Machek wrote: > > >> > > >> atl1c driver is doing order-4 allocation with GFP_ATOMIC > > >> priority. That often breaks networking after resume. Switch to > > >> GFP_KERNEL. Still not ideal, but should be significantly better. > > > > > > It is not clear why GFP_KERNEL can replace GFP_ATOMIC safely neither > > > from the changelog nor from the patch context. > > > > Earlier in the function we do a GFP_KERNEL kmalloc so: > > > > ¯\_(ツ)_/¯ > > > > It should be fine. > > > > AFAICT, the people who benefit from GFP_ATOMIC are the people running all > their storage over NFS/iSCSI who are suspending their machines while > they're so busy they don't have any clean order 4 pagecache to drop, and > want the machine to panic rather than hang. Why would GFP_KERNEL order-4 allocation hang? It will fail if there are not >=4 order pages available even after reclaim and/or compaction. GFP_ATOMIC allocations should be used only when an access to memory reserves is really required. If the allocation just doesn't want to invoke direct reclaim then GFP_NOWAIT is a more suitable alternative. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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