lkml.org 
[lkml]   [2022]   [Feb]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Do we really need SLOB nowdays?
On Wed, Dec 15, 2021 at 11:10:06AM +0100, Vlastimil Babka wrote:
> On 12/15/21 07:29, Hyeonggon Yoo wrote:
> > On Tue, Dec 14, 2021 at 06:24:58PM +0100, Vlastimil Babka wrote:
> >> On 12/10/21 13:06, Christoph Lameter wrote:
> >> > On Fri, 10 Dec 2021, Hyeonggon Yoo wrote:
> >> >
> >> >> > > (But I still have doubt if we can run linux on machines like that.)
> >> >> >
> >> >> > I sent you a series of articles about making Linux run in 1MB.
> >> >>
> >> >> After some time playing with the size of kernel,
> >> >> I was able to run linux in 6.6MiB of RAM. and the SLOB used
> >> >> around 300KiB of memory.
> >> >
> >> > What is the minimal size you need for SLUB?
> >>
> >
> > I don't know why Christoph's mail is not in my mailbox. maybe I deleted it
> > by mistake or I'm not cc-ed.
> >
> > Anyway, I tried to measure this again with SLUB and SLOB.
> >
> > SLUB uses few hundreds of bytes than SLOB.
> >
> > There isn't much difference in 'Memory required to boot'.
> > (interestingly SLUB requires less)
> >
> > 'Memory required to boot' is measured by reducing memory
> > until it says 'System is deadlocked on memory'. I don't know
> > exact reason why they differ.
> >
> > Note that the configuration is based on tinyconfig and
> > I added initramfs support + tty layer (+ uart driver) + procfs support,
> > + ELF binary support + etc.
> >
> > there isn't even block layer, but it's good starting point to see
> > what happens in small system.
> >
> > SLOB:
> >
> > Memory required to boot: 6950K
> >
> > Slab: 368 kB
> >
> > SLUB:
> > Memory required to boot: 6800K
> >
> > Slab: 552 kB
> >
> > SLUB with slab merging:
> >
> > Slab: 536 kB
>
> 168kB different on a system with less than 8MB memory looks rather
> significant to me to simply delete SLOB, I'm afraid.

Just FYI...
Some experiment based on v5.17-rc3:

SLOB:
Slab: 388 kB

SLUB:
Slab: 540 kB (+152kb)

SLUB with s->min_partial = 0:
Slab: 452 kB (+64kb)

SLUB with s->min_partial = 0 && slub_max_order = 0:
Slab: 436 kB (+48kb)

SLUB with s->min_partial = 0 && slub_max_order = 0
+ merging slabs crazily (just ignore SLAB_NEVER_MERGE/SLAB_MERGE_SAME):
Slab: 408 kB (+20kb)

Decreasing further seem to be hard and
I guess +20kb are due to partial slabs.

I think SLUB can be memory-efficient as SLOB.
Is SLOB (Address-Ordered next fit) stronger to fragmentation than SLUB?

\
 
 \ /
  Last update: 2022-02-18 11:14    [W:0.149 / U:2.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site