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Groups > linux.kernel > #1241294 > unrolled thread
| Started by | David Howells <dhowells@redhat.com> |
|---|---|
| First post | 2015-10-07 11:40 +0200 |
| Last post | 2015-10-07 16:00 +0200 |
| Articles | 3 — 2 participants |
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Re: [PATCH] change current_is_single_threaded() to use for_each_thread() David Howells <dhowells@redhat.com> - 2015-10-07 11:40 +0200
Re: [PATCH] change current_is_single_threaded() to use for_each_thread() Oleg Nesterov <oleg@redhat.com> - 2015-10-07 14:00 +0200
Re: [PATCH] change current_is_single_threaded() to use for_each_thread() David Howells <dhowells@redhat.com> - 2015-10-07 16:00 +0200
| From | David Howells <dhowells@redhat.com> |
|---|---|
| Date | 2015-10-07 11:40 +0200 |
| Subject | Re: [PATCH] change current_is_single_threaded() to use for_each_thread() |
| Message-ID | <qgTmx-P7-15@gated-at.bofh.it> |
Oleg Nesterov <oleg@redhat.com> wrote: > Change current_is_single_threaded() to use for_each_thread() rather > than deprecated while_each_thread(). Wouldn't the old way be more efficient, given there's always going to be at least one thread? Granted, it's not much of an efficiency boost... David -- 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 | Oleg Nesterov <oleg@redhat.com> |
|---|---|
| Date | 2015-10-07 14:00 +0200 |
| Subject | Re: [PATCH] change current_is_single_threaded() to use for_each_thread() |
| Message-ID | <qgVy3-3SB-21@gated-at.bofh.it> |
| In reply to | #1241294 |
On 10/07, David Howells wrote: > > Oleg Nesterov <oleg@redhat.com> wrote: > > > Change current_is_single_threaded() to use for_each_thread() rather > > than deprecated while_each_thread(). > > Wouldn't the old way be more efficient, given there's always going to be at > least one thread? Yes, unfortunately. Before this change (in the likely case) we never do next_thread(), after this patch we always do list_first_entry(). > Granted, it's not much of an efficiency boost... Yes, and while_each_thread() is buggy. See the changelog in 0c740d0afc "introduce for_each_thread() to replace the buggy while_each_thread(). Yes, the race is almost purely theoretical, but still. To clarify, we had some "real" bugs fixed by s/while_each_thread/ for_each_thread/, but only because while_each_thread() was used wrongly. for_each_thread() is more safe, it only needs the stable task_struct. Oleg. -- 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 | David Howells <dhowells@redhat.com> |
|---|---|
| Date | 2015-10-07 16:00 +0200 |
| Message-ID | <qgXqb-6Da-27@gated-at.bofh.it> |
| In reply to | #1241411 |
Oleg Nesterov <oleg@redhat.com> wrote: > To clarify, we had some "real" bugs fixed by s/while_each_thread/ > for_each_thread/, but only because while_each_thread() was used wrongly. > for_each_thread() is more safe, it only needs the stable task_struct. Fair enough. David -- 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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