Re: Mainline kernel OLTP performance update

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, 2009-01-22 at 11:15 +0200, Pekka Enberg wrote:
> On Thu, 2009-01-22 at 16:36 +0800, Zhang, Yanmin wrote:
> > On Wed, 2009-01-21 at 18:58 -0500, Christoph Lameter wrote:
> > > On Tue, 20 Jan 2009, Zhang, Yanmin wrote:
> > > 
> > > > kmem_cache skbuff_head_cache's object size is just 256, so it shares the kmem_cache
> > > > with :0000256. Their order is 1 which means every slab consists of 2 physical pages.
> > > 
> > > That order can be changed. Try specifying slub_max_order=0 on the kernel
> > > command line to force an order 0 alloc.
> > I tried slub_max_order=0 and there is no improvement on this UDP-U-4k issue.
> > Both get_page_from_freelist and __free_pages_ok's cpu time are still very high.
> > 
> > I checked my instrumentation in kernel and found it's caused by large object allocation/free
> > whose size is more than PAGE_SIZE. Here its order is 1.
> > 
> > The right free callchain is __kfree_skb => skb_release_all => skb_release_data.
> > 
> > So this case isn't the issue that batch of allocation/free might erase partial page
> > functionality.
> 
> So is this the kfree(skb->head) in skb_release_data() or the put_page()
> calls in the same function in a loop?
It's kfree(skb->head).

> 
> If it's the former, with big enough size passed to __alloc_skb(), the
> networking code might be taking a hit from the SLUB page allocator
> pass-through.


--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Linux IIO]     [Samba]     [Device Mapper]
  Powered by Linux