search for: steal_tag

...freelists. On allocation failure if > enough cpus have tags that there could potentially be (nr_tags / 2) tags > stuck on remote percpu freelists, we then pick a remote cpu at random to > steal from. > > Note that there's no cpu hotplug notifier - we don't care, because > steal_tags() will eventually get the down cpu's tags. We _could_ satisfy > more allocations if we had a notifier - but we'll still meet our > guarantees and it's absolutely not a correctness issue, so I don't think > it's worth the extra code. > > ... > > include/lin...

...freelists. On allocation failure if > enough cpus have tags that there could potentially be (nr_tags / 2) tags > stuck on remote percpu freelists, we then pick a remote cpu at random to > steal from. > > Note that there's no cpu hotplug notifier - we don't care, because > steal_tags() will eventually get the down cpu's tags. We _could_ satisfy > more allocations if we had a notifier - but we'll still meet our > guarantees and it's absolutely not a correctness issue, so I don't think > it's worth the extra code. > > ... > > include/lin...

On Tue, Aug 20, 2013 at 02:31:57PM -0700, Andrew Morton wrote: > On Fri, 16 Aug 2013 23:09:06 +0000 "Nicholas A. Bellinger" <nab at linux-iscsi.org> wrote: > > + /* > > + * Bitmap of cpus that (may) have tags on their percpu freelists: > > + * steal_tags() uses this to decide when to steal tags, and which cpus > > + * to try stealing from. > > + * > > + * It's ok for a freelist to be empty when its bit is set - steal_tags() > > + * will just keep looking - but the bitmap _must_ be set whenever a > > + * percp...

...pus have tags on their percpu freelists. On allocation failure if enough cpus have tags that there could potentially be (nr_tags / 2) tags stuck on remote percpu freelists, we then pick a remote cpu at random to steal from. Note that there's no cpu hotplug notifier - we don't care, because steal_tags() will eventually get the down cpu's tags. We _could_ satisfy more allocations if we had a notifier - but we'll still meet our guarantees and it's absolutely not a correctness issue, so I don't think it's worth the extra code. Signed-off-by: Kent Overstreet <koverstreet at...

On Wed, 28 Aug 2013 12:53:17 -0700 Kent Overstreet <kmo at daterainc.com> wrote: > > > + while (1) { > > > + spin_lock(&pool->lock); > > > + > > > + /* > > > + * prepare_to_wait() must come before steal_tags(), in case > > > + * percpu_ida_free() on another cpu flips a bit in > > > + * cpus_have_tags > > > + * > > > + * global lock held and irqs disabled, don't need percpu lock > > > + */ > > > + prepare_to_wait(&pool->wait, &...

On Wed, 28 Aug 2013 12:53:17 -0700 Kent Overstreet <kmo at daterainc.com> wrote: > > > + while (1) { > > > + spin_lock(&pool->lock); > > > + > > > + /* > > > + * prepare_to_wait() must come before steal_tags(), in case > > > + * percpu_ida_free() on another cpu flips a bit in > > > + * cpus_have_tags > > > + * > > > + * global lock held and irqs disabled, don't need percpu lock > > > + */ > > > + prepare_to_wait(&pool->wait, &...

From: Nicholas Bellinger <nab at linux-iscsi.org> Hi folks, This is an updated series for adding tag pre-allocation support of target fabric descriptor memory, utilizing Kent's latest per-cpu ida bits here, along with Christoph Lameter's latest comments: [PATCH 04/10] idr: Percpu ida http://marc.info/?l=linux-kernel&m=137160026006974&w=2 The first patch is a

From: Nicholas Bellinger <nab at linux-iscsi.org> Hi folks, This is an updated series for adding tag pre-allocation support of target fabric descriptor memory, utilizing Kent's latest per-cpu ida bits here, along with Christoph Lameter's latest comments: [PATCH 04/10] idr: Percpu ida http://marc.info/?l=linux-kernel&m=137160026006974&w=2 The first patch is a

...ote: > On Wed, 28 Aug 2013 12:53:17 -0700 Kent Overstreet <kmo at daterainc.com> wrote: > > > > > + while (1) { > > > > + spin_lock(&pool->lock); > > > > + > > > > + /* > > > > + * prepare_to_wait() must come before steal_tags(), in case > > > > + * percpu_ida_free() on another cpu flips a bit in > > > > + * cpus_have_tags > > > > + * > > > > + * global lock held and irqs disabled, don't need percpu lock > > > > + */ > > > > + prepare...

...3) / 2) struct percpu_ida_cpu { + /* + * Even though this is percpu, we need a lock for tag stealing by remote + * CPUs: + */ spinlock_t lock; + + /* nr_free/freelist form a stack of free IDs */ unsigned nr_free; unsigned freelist[]; }; @@ -1209,21 +1215,21 @@ static inline void steal_tags(struct percpu_ida *pool, unsigned cpus_have_tags, cpu = pool->cpu_last_stolen; struct percpu_ida_cpu *remote; - for (cpus_have_tags = bitmap_weight(pool->cpus_have_tags, nr_cpu_ids); + for (cpus_have_tags = cpumask_weight(&pool->cpus_have_tags); cpus_have_tags * IDA_PCPU_...

Removing the percpu_ida code nets over 400 lines of removal. It's not as spectacular as deleting an entire architecture, but it's still a worthy reduction in lines of code. Untested due to lack of hardware and not understanding how to set up a target platform. Changes from v1: - Fixed bugs pointed out by Jens in iscsit_wait_for_tag() - Abstracted out tag freeing as requested by Bart

Removing the percpu_ida code nets over 400 lines of removal. It's not as spectacular as deleting an entire architecture, but it's still a worthy reduction in lines of code. Untested due to lack of hardware and not understanding how to set up a target platform. Changes from v1: - Fixed bugs pointed out by Jens in iscsit_wait_for_tag() - Abstracted out tag freeing as requested by Bart

From: Matthew Wilcox <mawilcox at microsoft.com> This is a pretty rough-and-ready conversion of the target drivers from using percpu_ida to sbitmap. It compiles; I don't have a target setup, so it's completely untested. I haven't tried to do anything particularly clever here, so it's possible that, for example, the wait queue in iscsi_target_util could be more clever, like