From: "DERUMIER, Alexandre" <Alexandre.DERUMIER@groupe-cyllene.com>
To: "pve-devel@lists.proxmox.com" <pve-devel@lists.proxmox.com>
Cc: "t.lamprecht@proxmox.com" <t.lamprecht@proxmox.com>
Subject: Re: [pve-devel] applied: [RFC pve-qemu] disable jemalloc
Date: Fri, 10 Mar 2023 18:05:29 +0000 [thread overview]
Message-ID: <5d774074596e5430faaa26146c70fdd13b513598.camel@groupe-cyllene.com> (raw)
In-Reply-To: <3dd51877-142c-55b2-e2ed-33f48ecb348f@proxmox.com>
Hi,
sorry for bumping this old thread.
I'm currently benching again qemu with librbd and memory allocator.
It's seem that they are still performance problem with default glibc
allocator, around 20-25% less iops and bigger latency.
From my bench, i'm around 60k iops vs 80-90k iops with 4k randread.
Redhat have also notice it
https://bugzilla.redhat.com/show_bug.cgi?id=1717414
https://sourceware.org/bugzilla/show_bug.cgi?id=28050
I known than jemalloc was buggy with rust lib && pbs block driver,
but did you have evaluated tcmalloc ?
Note that it's possible to load it dynamically with LD_PRELOAD,
so maybe could we add an option in vm config to enable it ?
Le mardi 15 décembre 2020 à 14:43 +0100, Thomas Lamprecht a écrit :
> On 10.12.20 16:23, Stefan Reiter wrote:
> > jemalloc does not play nice with our Rust library (proxmox-backup-
> > qemu),
> > specifically it never releases memory allocated from Rust to the
> > OS.
> > This leads to a problem with larger caches (e.g. for the PBS block
> > driver).
> >
> > It appears to be related to this GitHub issue:
> > https://github.com/jemalloc/jemalloc/issues/1398
> >
> > The background_thread solution seems weirdly hacky, so let's
> > disable
> > jemalloc entirely for now.
> >
> > Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
> > ---
> >
> > @Alexandre: you were the one to introduce jemalloc into our QEMU
> > builds a long
> > time ago - does it still provide a measurable benefit? If the
> > performance loss
> > would be too great in removing it, we could maybe figure out some
> > workarounds as
> > well.
> >
> > Its current behaviour does seem rather broken to me though...
> >
> > debian/rules | 1 -
> > 1 file changed, 1 deletion(-)
> >
> >
>
> applied, thanks!
>
>
> _______________________________________________
> pve-devel mailing list
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>
next prev parent reply other threads:[~2023-03-10 18:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-10 15:23 [pve-devel] " Stefan Reiter
2020-12-11 15:21 ` alexandre derumier
2020-12-15 13:43 ` [pve-devel] applied: " Thomas Lamprecht
2023-03-10 18:05 ` DERUMIER, Alexandre [this message]
2023-03-11 9:01 ` Thomas Lamprecht
[not found] <1c4d80a05d8328a52b9d15e991fd4d348bce1327.camel@groupe-cyllene.com>
2023-03-11 13:14 ` DERUMIER, Alexandre
2023-03-13 7:17 ` DERUMIER, Alexandre
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