I realized I forgot to follow-up on this thread. Just to be clear, I
have confirmed that I am seeing what to me is undesirable behavior
even with the ARC being 1500 MB in size on an almost idle system (<
0.5 mb/sec read load, almost 0 write load). Observe these recursive
searches through /usr/src/s
Hi,
In simple terms, the ARC is divided into a MRU and MFU side.
target size (c) = target MRU size (p) + target MFU size (c-p)
On Solaris, to get from the MRU to the MFU side, the block must be
read at least once in 62.5 milliseconds. For pure read-once workloads,
the data won't to the M
On Apr 5, 2010, at 3:24 PM, Peter Schuller wrote:
> I will have to look into it in better detail to understand the
> consequences. Is there a paper that describes the ARC as it is
> implemented in ZFS (since it clearly diverges from the IBM ARC)?
There are various blogs, but perhaps the best docum
On 04/05/10 15:24, Peter Schuller wrote:
In the urxvt case, I am basing my claim on informal observations.
I.e., "hit terminal launch key, wait for disks to rattle, get my
terminal". Repeat. Only by repeating it very many times in very rapid
succession am I able to coerce it to be cached such tha
> In simple terms, the ARC is divided into a MRU and MFU side.
> target size (c) = target MRU size (p) + target MFU size (c-p)
>
> On Solaris, to get from the MRU to the MFU side, the block must be
> read at least once in 62.5 milliseconds. For pure read-once workloads,
> the data won't to
On Apr 5, 2010, at 2:23 PM, Peter Schuller wrote:
> That's a very general statement. I am talking about specifics here.
> For example, you can have mountains of evidence that shows that a
> plain LRU is "optimal" (under some conditions). That doesn't change
> the fact that if I want to avoid a sequ
> The ARC is designed to use as much memory as is available up to a limit. If
> the kernel allocator needs memory and there is none available, then the
> allocator requests memory back from the zfs ARC. Note that some systems have
> multiple memory allocators. For example, there may be a memory a
On Mon, 5 Apr 2010, Peter Schuller wrote:
It may be FreeBSD specific, but note that I a not talking about the
amount of memory dedicated to the ARC and how it balances with free
memory on the system. I am talking about eviction policy. I could be
wrong but I didn't think ZFS port made significan
> It sounds like you are complaining about how FreeBSD has implemented zfs in
> the system rather than about zfs in general. These problems don't occur
> under Solaris. Zfs and the kernel need to agree on how to allocate/free
> memory, and it seems that Solaris is more advanced than FreeBSD in th
On Mon, 5 Apr 2010, Peter Schuller wrote:
For desktop use, and presumably rapidly changing non-desktop uses, I
find the ARC cache pretty annoying in its behavior. For example this
morning I had to hit my launch-terminal key perhaps 50 times (roughly)
before it would start completing without disk
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