Messages in this thread | | | Subject | Re: [PATCH V2] mlx4_core: allocate ICM memory in page size chunks | From | Tariq Toukan <> | Date | Sun, 13 May 2018 12:00:35 +0300 |
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On 11/05/2018 10:23 PM, Qing Huang wrote: > When a system is under memory presure (high usage with fragments), > the original 256KB ICM chunk allocations will likely trigger kernel > memory management to enter slow path doing memory compact/migration > ops in order to complete high order memory allocations. > > When that happens, user processes calling uverb APIs may get stuck > for more than 120s easily even though there are a lot of free pages > in smaller chunks available in the system. > > Syslog: > ... > Dec 10 09:04:51 slcc03db02 kernel: [397078.572732] INFO: task > oracle_205573_e:205573 blocked for more than 120 seconds. > ... > > With 4KB ICM chunk size on x86_64 arch, the above issue is fixed. > > However in order to support smaller ICM chunk size, we need to fix > another issue in large size kcalloc allocations. > > E.g. > Setting log_num_mtt=30 requires 1G mtt entries. With the 4KB ICM chunk > size, each ICM chunk can only hold 512 mtt entries (8 bytes for each mtt > entry). So we need a 16MB allocation for a table->icm pointer array to > hold 2M pointers which can easily cause kcalloc to fail. > > The solution is to use vzalloc to replace kcalloc. There is no need > for contiguous memory pages for a driver meta data structure (no need > of DMA ops). > > Signed-off-by: Qing Huang <qing.huang@oracle.com> > Acked-by: Daniel Jurgens <danielj@mellanox.com> > Reviewed-by: Zhu Yanjun <yanjun.zhu@oracle.com> > --- > v2 -> v1: adjusted chunk size to reflect different architectures. > > drivers/net/ethernet/mellanox/mlx4/icm.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/drivers/net/ethernet/mellanox/mlx4/icm.c b/drivers/net/ethernet/mellanox/mlx4/icm.c > index a822f7a..ccb62b8 100644 > --- a/drivers/net/ethernet/mellanox/mlx4/icm.c > +++ b/drivers/net/ethernet/mellanox/mlx4/icm.c > @@ -43,12 +43,12 @@ > #include "fw.h" > > /* > - * We allocate in as big chunks as we can, up to a maximum of 256 KB > - * per chunk. > + * We allocate in page size (default 4KB on many archs) chunks to avoid high > + * order memory allocations in fragmented/high usage memory situation. > */ > enum { > - MLX4_ICM_ALLOC_SIZE = 1 << 18, > - MLX4_TABLE_CHUNK_SIZE = 1 << 18 > + MLX4_ICM_ALLOC_SIZE = 1 << PAGE_SHIFT, > + MLX4_TABLE_CHUNK_SIZE = 1 << PAGE_SHIFT
Which is actually PAGE_SIZE. Also, please add a comma at the end of the last entry.
> }; > > static void mlx4_free_icm_pages(struct mlx4_dev *dev, struct mlx4_icm_chunk *chunk) > @@ -400,7 +400,7 @@ int mlx4_init_icm_table(struct mlx4_dev *dev, struct mlx4_icm_table *table, > obj_per_chunk = MLX4_TABLE_CHUNK_SIZE / obj_size; > num_icm = (nobj + obj_per_chunk - 1) / obj_per_chunk; > > - table->icm = kcalloc(num_icm, sizeof(*table->icm), GFP_KERNEL); > + table->icm = vzalloc(num_icm * sizeof(*table->icm));
Why not kvzalloc ?
> if (!table->icm) > return -ENOMEM; > table->virt = virt; > @@ -446,7 +446,7 @@ int mlx4_init_icm_table(struct mlx4_dev *dev, struct mlx4_icm_table *table, > mlx4_free_icm(dev, table->icm[i], use_coherent); > } > > - kfree(table->icm); > + vfree(table->icm); > > return -ENOMEM; > } > @@ -462,5 +462,5 @@ void mlx4_cleanup_icm_table(struct mlx4_dev *dev, struct mlx4_icm_table *table) > mlx4_free_icm(dev, table->icm[i], table->coherent); > } > > - kfree(table->icm); > + vfree(table->icm); > } >
Thanks for your patch.
I need to verify there is no dramatic performance degradation here. You can prepare and send a v3 in the meanwhile.
Thanks, Tariq
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