> Subject: Re: [PATCH v2 repost 4/7] virtio-balloon: speed up inflate/deflate > process > > On Wed, Jul 27, 2016 at 09:03:21AM -0700, Dave Hansen wrote: > > On 07/26/2016 06:23 PM, Liang Li wrote: > > > + vb->pfn_limit = VIRTIO_BALLOON_PFNS_LIMIT; > > > + vb->pfn_limit = min(vb->pfn_limit, get_max_pfn()); > > > + vb->bmap_len = ALIGN(vb->pfn_limit, BITS_PER_LONG) / > > > + BITS_PER_BYTE + 2 * sizeof(unsigned long); > > > + hdr_len = sizeof(struct balloon_bmap_hdr); > > > + vb->bmap_hdr = kzalloc(hdr_len + vb->bmap_len, GFP_KERNEL); > > > > This ends up doing a 1MB kmalloc() right? That seems a _bit_ big. > > How big was the pfn buffer before? > > > Yes I would limit this to 1G memory in a go, will result in a 32KByte bitmap. > > -- > MST Limit to 1G is bad for the performance, I sent you the test result several weeks ago. Paste it bellow: ------------------------------------------------------------------------------------------------------------------------ About the size of page bitmap, I have test the performance of filling the balloon to 15GB with a 16GB RAM VM. =============================== 32K Byte (cover 1GB of RAM) Time spends on inflating: 2031ms --------------------------------------------- 64K Byte (cover 2GB of RAM) Time spends on inflating: 1507ms -------------------------------------------- 512K Byte (cover 16GB of RAM) Time spends on inflating: 1237ms ================================ If possible, a big bitmap is better for performance. Liang -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
