Messages in this thread | | | Date | Mon, 13 Dec 2021 08:21:29 -0600 | Subject | Re: [PATCH v3 2/5] dma-pool: allow user to disable atomic pool | From | john.p.donnelly@oracle ... |
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On 12/13/21 6:27 AM, Baoquan He wrote: > In the current code, three atomic memory pools are always created, > atomic_pool_kernel|dma|dma32, even though 'coherent_pool=0' is > specified in kernel command line. In fact, atomic pool is only > necessary when CONFIG_DMA_DIRECT_REMAP=y or mem_encrypt_active=y > which are needed on few ARCHes. > > So change code to allow user to disable atomic pool by specifying > 'coherent_pool=0'. > > Meanwhile, update the relevant document in kernel-parameter.txt. > > Signed-off-by: Baoquan He <bhe@redhat.com> > Acked-by: John Donnelly <john.p.donnelly@oracle.com> Tested-by: John Donnelly <john.p.donnelly@oracle.com>
> --- > Documentation/admin-guide/kernel-parameters.txt | 3 ++- > kernel/dma/pool.c | 7 +++++-- > 2 files changed, 7 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index ec4d25e854a8..d7015309614b 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -664,7 +664,8 @@ > > coherent_pool=nn[KMG] [ARM,KNL] > Sets the size of memory pool for coherent, atomic dma > - allocations. Otherwise the default size will be scaled > + allocations. A value of 0 disables the three atomic > + memory pool. Otherwise the default size will be scaled > with memory capacity, while clamped between 128K and > 1 << (PAGE_SHIFT + MAX_ORDER-1). > > diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c > index 5f84e6cdb78e..5a85804b5beb 100644 > --- a/kernel/dma/pool.c > +++ b/kernel/dma/pool.c > @@ -21,7 +21,7 @@ static struct gen_pool *atomic_pool_kernel __ro_after_init; > static unsigned long pool_size_kernel; > > /* Size can be defined by the coherent_pool command line */ > -static size_t atomic_pool_size; > +static unsigned long atomic_pool_size = -1; > > /* Dynamic background expansion when the atomic pool is near capacity */ > static struct work_struct atomic_pool_work; > @@ -188,11 +188,14 @@ static int __init dma_atomic_pool_init(void) > { > int ret = 0; > > + if (!atomic_pool_size) > + return 0; > + > /* > * If coherent_pool was not used on the command line, default the pool > * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1. > */ > - if (!atomic_pool_size) { > + if (atomic_pool_size == -1) { > unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K); > pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES); > atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);
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