| Message ID | 20240312140532.64124-1-sxwjean@me.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm/slub: Simplify get_partial_node() | expand |
On 2024/3/12 22:05, sxwjean@me.com wrote: > From: Xiongwei Song <xiongwei.song@windriver.com> > > Remove the check of !kmem_cache_has_cpu_partial() because it is always > false, we've known this by calling kmem_cache_debug() before calling > remove_partial(), so we can remove the check. > > Meanwhile, redo filling cpu partial and add comment to improve the > readability. > > Signed-off-by: Xiongwei Song <xiongwei.song@windriver.com> > --- > Changes in v2: > - Use "#if IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL)" to instead > "if (IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL))" to fix build error. > (Thanks Chengming Zhou) > - Add __maybe_unused for partial_slabs to prevent compiler warning. > > v1: > https://lore.kernel.org/linux-kernel/20240311132720.37741-1-sxwjean@me.com/T/ > --- > mm/slub.c | 24 +++++++++++++----------- > 1 file changed, 13 insertions(+), 11 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index a3ab096c38c0..ab526960ee5b 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2588,7 +2588,7 @@ static struct slab *get_partial_node(struct kmem_cache *s, > { > struct slab *slab, *slab2, *partial = NULL; > unsigned long flags; > - unsigned int partial_slabs = 0; > + unsigned int __maybe_unused partial_slabs = 0; > > /* > * Racy check. If we mistakenly see no partial slabs then we > @@ -2620,19 +2620,21 @@ static struct slab *get_partial_node(struct kmem_cache *s, > if (!partial) { > partial = slab; > stat(s, ALLOC_FROM_PARTIAL); > - } else { > - put_cpu_partial(s, slab, 0); > - stat(s, CPU_PARTIAL_NODE); > - partial_slabs++; > + > + /* Fill cpu partial if needed from next iteration, or break */ > + if (IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL)) > + continue; > + else > + break; > } > -#ifdef CONFIG_SLUB_CPU_PARTIAL > - if (!kmem_cache_has_cpu_partial(s) > - || partial_slabs > s->cpu_partial_slabs / 2) > + > +#if IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL) Hmm, these two CONFIG_SLUB_CPU_PARTIAL look verbose to me :( How about using just one, maybe like this? diff --git a/mm/slub.c b/mm/slub.c index 2ef88bbf56a3..a018c715b648 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2620,19 +2620,16 @@ static struct slab *get_partial_node(struct kmem_cache *s, if (!partial) { partial = slab; stat(s, ALLOC_FROM_PARTIAL); +#ifdef CONFIG_SLUB_CPU_PARTIAL } else { put_cpu_partial(s, slab, 0); stat(s, CPU_PARTIAL_NODE); - partial_slabs++; - } -#ifdef CONFIG_SLUB_CPU_PARTIAL - if (!kmem_cache_has_cpu_partial(s) - || partial_slabs > s->cpu_partial_slabs / 2) - break; + if (++partial_slabs > s->cpu_partial_slabs / 2) + break; #else - break; + break; #endif - + } } spin_unlock_irqrestore(&n->list_lock, flags); return partial; > + put_cpu_partial(s, slab, 0); > + stat(s, CPU_PARTIAL_NODE); > + > + if (++partial_slabs > s->cpu_partial_slabs/2) > break; > -#else > - break; > #endif > - > } > spin_unlock_irqrestore(&n->list_lock, flags); > return partial;
> On 2024/3/12 22:05, sxwjean@me.com wrote: > > From: Xiongwei Song <xiongwei.song@windriver.com> > > > > Remove the check of !kmem_cache_has_cpu_partial() because it is always > > false, we've known this by calling kmem_cache_debug() before calling > > remove_partial(), so we can remove the check. > > > > Meanwhile, redo filling cpu partial and add comment to improve the > > readability. > > > > Signed-off-by: Xiongwei Song <xiongwei.song@windriver.com> > > --- > > Changes in v2: > > - Use "#if IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL)" to instead > > "if (IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL))" to fix build error. > > (Thanks Chengming Zhou) > > - Add __maybe_unused for partial_slabs to prevent compiler warning. > > > > v1: > > https://lore.kernel.org/linux-kernel/20240311132720.37741-1-sxwjean@me.com/T/ > > --- > > mm/slub.c | 24 +++++++++++++----------- > > 1 file changed, 13 insertions(+), 11 deletions(-) > > > > diff --git a/mm/slub.c b/mm/slub.c > > index a3ab096c38c0..ab526960ee5b 100644 > > --- a/mm/slub.c > > +++ b/mm/slub.c > > @@ -2588,7 +2588,7 @@ static struct slab *get_partial_node(struct kmem_cache *s, > > { > > struct slab *slab, *slab2, *partial = NULL; > > unsigned long flags; > > - unsigned int partial_slabs = 0; > > + unsigned int __maybe_unused partial_slabs = 0; > > > > /* > > * Racy check. If we mistakenly see no partial slabs then we > > @@ -2620,19 +2620,21 @@ static struct slab *get_partial_node(struct kmem_cache *s, > > if (!partial) { > > partial = slab; > > stat(s, ALLOC_FROM_PARTIAL); > > - } else { > > - put_cpu_partial(s, slab, 0); > > - stat(s, CPU_PARTIAL_NODE); > > - partial_slabs++; > > + > > + /* Fill cpu partial if needed from next iteration, or break */ > > + if (IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL)) > > + continue; > > + else > > + break; > > } > > -#ifdef CONFIG_SLUB_CPU_PARTIAL > > - if (!kmem_cache_has_cpu_partial(s) > > - || partial_slabs > s->cpu_partial_slabs / 2) > > + > > +#if IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL) > > Hmm, these two CONFIG_SLUB_CPU_PARTIAL look verbose to me :( > > How about using just one, maybe like this? > > diff --git a/mm/slub.c b/mm/slub.c > index 2ef88bbf56a3..a018c715b648 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2620,19 +2620,16 @@ static struct slab *get_partial_node(struct kmem_cache *s, > if (!partial) { > partial = slab; > stat(s, ALLOC_FROM_PARTIAL); > +#ifdef CONFIG_SLUB_CPU_PARTIAL > } else { I don't like splitting "if...else..." up with preprocessor directives personally. It's messy for me.
On Wed, 13 Mar 2024, Song, Xiongwei wrote: > > On 2024/3/12 22:05, sxwjean@me.com wrote: > > > From: Xiongwei Song <xiongwei.song@windriver.com> > > > > > > Remove the check of !kmem_cache_has_cpu_partial() because it is always > > > false, we've known this by calling kmem_cache_debug() before calling > > > remove_partial(), so we can remove the check. > > > > > > Meanwhile, redo filling cpu partial and add comment to improve the > > > readability. > > > > > > Signed-off-by: Xiongwei Song <xiongwei.song@windriver.com> > > > --- > > > Changes in v2: > > > - Use "#if IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL)" to instead > > > "if (IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL))" to fix build error. > > > (Thanks Chengming Zhou) > > > - Add __maybe_unused for partial_slabs to prevent compiler warning. > > > > > > v1: > > > https://lore.kernel.org/linux-kernel/20240311132720.37741-1-sxwjean@me.com/T/ > > > --- > > > mm/slub.c | 24 +++++++++++++----------- > > > 1 file changed, 13 insertions(+), 11 deletions(-) > > > > > > diff --git a/mm/slub.c b/mm/slub.c > > > index a3ab096c38c0..ab526960ee5b 100644 > > > --- a/mm/slub.c > > > +++ b/mm/slub.c > > > @@ -2588,7 +2588,7 @@ static struct slab *get_partial_node(struct kmem_cache *s, > > > { > > > struct slab *slab, *slab2, *partial = NULL; > > > unsigned long flags; > > > - unsigned int partial_slabs = 0; > > > + unsigned int __maybe_unused partial_slabs = 0; > > > > > > /* > > > * Racy check. If we mistakenly see no partial slabs then we > > > @@ -2620,19 +2620,21 @@ static struct slab *get_partial_node(struct kmem_cache *s, > > > if (!partial) { > > > partial = slab; > > > stat(s, ALLOC_FROM_PARTIAL); > > > - } else { > > > - put_cpu_partial(s, slab, 0); > > > - stat(s, CPU_PARTIAL_NODE); > > > - partial_slabs++; > > > + > > > + /* Fill cpu partial if needed from next iteration, or break */ > > > + if (IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL)) > > > + continue; > > > + else > > > + break; > > > } > > > -#ifdef CONFIG_SLUB_CPU_PARTIAL > > > - if (!kmem_cache_has_cpu_partial(s) > > > - || partial_slabs > s->cpu_partial_slabs / 2) > > > + > > > +#if IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL) > > > > Hmm, these two CONFIG_SLUB_CPU_PARTIAL look verbose to me :( > > > > How about using just one, maybe like this? > > > > diff --git a/mm/slub.c b/mm/slub.c > > index 2ef88bbf56a3..a018c715b648 100644 > > --- a/mm/slub.c > > +++ b/mm/slub.c > > @@ -2620,19 +2620,16 @@ static struct slab *get_partial_node(struct kmem_cache *s, > > if (!partial) { > > partial = slab; > > stat(s, ALLOC_FROM_PARTIAL); > > +#ifdef CONFIG_SLUB_CPU_PARTIAL > > } else { > > I don't like splitting "if...else..." up with preprocessor directives personally. It's messy for me. > I would agree, but the flow here actually seems like it's easier to follow if we are checking for CONFIG_SLUB_CPU_PARTIAL in multiple places :/
diff --git a/mm/slub.c b/mm/slub.c index a3ab096c38c0..ab526960ee5b 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2588,7 +2588,7 @@ static struct slab *get_partial_node(struct kmem_cache *s, { struct slab *slab, *slab2, *partial = NULL; unsigned long flags; - unsigned int partial_slabs = 0; + unsigned int __maybe_unused partial_slabs = 0; /* * Racy check. If we mistakenly see no partial slabs then we @@ -2620,19 +2620,21 @@ static struct slab *get_partial_node(struct kmem_cache *s, if (!partial) { partial = slab; stat(s, ALLOC_FROM_PARTIAL); - } else { - put_cpu_partial(s, slab, 0); - stat(s, CPU_PARTIAL_NODE); - partial_slabs++; + + /* Fill cpu partial if needed from next iteration, or break */ + if (IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL)) + continue; + else + break; } -#ifdef CONFIG_SLUB_CPU_PARTIAL - if (!kmem_cache_has_cpu_partial(s) - || partial_slabs > s->cpu_partial_slabs / 2) + +#if IS_ENABLED(CONFIG_SLUB_CPU_PARTIAL) + put_cpu_partial(s, slab, 0); + stat(s, CPU_PARTIAL_NODE); + + if (++partial_slabs > s->cpu_partial_slabs/2) break; -#else - break; #endif - } spin_unlock_irqrestore(&n->list_lock, flags); return partial;