Hi again, I have redone a lot of tests,
with raw on nfs --------------- Patch 3/3, fix my problem (not apply patch 1/3 and patch 2/3). without patch 3/3, I'm seeing a lot of lseek, can take some minutes with guest hang. with patch 3/3, it almost take no time to generate the bitmap, no guest hang . (I have tested with differents raw files, different sizes) with raw on ext3 ---------------- Here, this hurt a lot. Not with every disk, but with some disks is totaly hanging the guest ----------------------- PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 4387 root 20 0 8985788 288900 12532 R 99.3 1.8 2:50.82 qemu 10.27% [kernel] [k] ext4_es_find_delayed_extent_range 9.64% [kernel] [k] _raw_read_lock 9.17% [kernel] [k] ext4_es_lookup_extent 6.63% [kernel] [k] down_read 5.49% [kernel] [k] ext4_map_blocks 4.82% [kernel] [k] up_read 3.09% [kernel] [k] ext4_ind_map_blocks 2.58% [kernel] [k] ext4_block_to_path.isra.9 2.18% [kernel] [k] kvm_arch_vcpu_ioctl_run 1.99% [kernel] [k] vmx_get_segment 1.99% [kernel] [k] ext4_llseek 1.62% [kernel] [k] ext4_get_branch 1.43% [kernel] [k] vmx_segment_access_rights.isra.28.part.29 1.23% [kernel] [k] x86_decode_insn 1.00% [kernel] [k] copy_user_generic_string 0.83% [kernel] [k] x86_emulate_instruction 0.81% [kernel] [k] rmode_segment_valid 0.78% [kernel] [k] gfn_to_hva_prot 0.74% [kernel] [k] __es_tree_search 0.73% [kernel] [k] do_insn_fetch 0.70% [kernel] [k] vmx_vcpu_run 0.69% [kernel] [k] vmx_read_guest_seg_selector 0.67% [kernel] [k] vmcs_writel 0.64% [kernel] [k] init_emulate_ctxt 0.62% [kernel] [k] native_write_msr_safe 0.61% [kernel] [k] kvm_apic_has_interrupt 0.57% [kernel] [k] vmx_handle_external_intr 0.57% [kernel] [k] x86_emulate_insn 0.56% [kernel] [k] vmx_handle_exit 0.50% [kernel] [k] native_read_tsc 0.47% [kernel] [k] _cond_resched 0.46% [kernel] [k] decode_operand 0.44% [kernel] [k] __srcu_read_lock 0.41% [kernel] [k] __linearize.isra.25 0.41% [kernel] [k] vmx_read_l1_tsc 0.39% [kernel] [k] clear_page_c 0.39% [kernel] [k] vmx_get_interrupt_shadow 0.36% [kernel] [k] vmx_set_interrupt_shadow Seem to be a known kernel bug: http://qemu.11.n7.nabble.com/Re-2-Strange-problems-with-lseek-in-qemu-img-map-td334414.html http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=14516bb7bb6ffbd49f35389f9ece3b2045ba5815 So, I think patch 3/3 is enough. (could be great to have it for qemu 2.4) Thanks again Fam for your hard work. Regards, Alexandre ----- Mail original ----- De: "aderumier" <aderum...@odiso.com> À: "Fam Zheng" <f...@redhat.com> Cc: "Kevin Wolf" <kw...@redhat.com>, "Stefan Hajnoczi" <stefa...@gmail.com>, "qemu-devel" <qemu-devel@nongnu.org>, qemu-bl...@nongnu.org Envoyé: Vendredi 10 Juillet 2015 12:36:40 Objet: Re: [Qemu-devel] [Qemu-block] [PATCH 0/3] mirror: Fix guest responsiveness during bitmap scan >>Does it completely hang? yes, can't ping network, and vnc console is frozen. >>What does "perf top" show? I'll do test today . (I'm going to vacation this night,I'll try to send results before that) ----- Mail original ----- De: "Fam Zheng" <f...@redhat.com> À: "aderumier" <aderum...@odiso.com> Cc: "Stefan Hajnoczi" <stefa...@gmail.com>, "Kevin Wolf" <kw...@redhat.com>, "qemu-devel" <qemu-devel@nongnu.org>, qemu-bl...@nongnu.org Envoyé: Vendredi 10 Juillet 2015 09:13:33 Objet: Re: [Qemu-devel] [Qemu-block] [PATCH 0/3] mirror: Fix guest responsiveness during bitmap scan On Fri, 07/10 08:54, Alexandre DERUMIER wrote: > >>Thinking about this again, I doubt > >>that lengthening the duration with a hardcoded value benifits everyone; and > >>before Alexandre's reply on old server/slow disks > > With 1ms sleep, I can reproduce the hang 100% with a fast cpu (xeon e5 v3 > 3,1ghz) and source raw file on nfs. Does it completely hang? I can't reproduce this with my machine mirroring from nfs to local: the guest runs smoothly. What does "perf top" show? Fam > > > ----- Mail original ----- > De: "Fam Zheng" <f...@redhat.com> > À: "Stefan Hajnoczi" <stefa...@gmail.com> > Cc: "Kevin Wolf" <kw...@redhat.com>, "qemu-devel" <qemu-devel@nongnu.org>, > qemu-bl...@nongnu.org > Envoyé: Vendredi 10 Juillet 2015 08:43:50 > Objet: Re: [Qemu-devel] [Qemu-block] [PATCH 0/3] mirror: Fix guest > responsiveness during bitmap scan > > On Thu, 07/09 14:02, Stefan Hajnoczi wrote: > > This patch only converts the mirror block job to use the new relax > > function. The other block jobs (stream, backup, commit) are still using > > a 0 ns delay and are therefore broken. They should probably be > > converted in the same series. > > That's because they all can be perfectly mitigated by setting a reasonable > "speed" that matchs the host horsepower. Thinking about this again, I doubt > that lengthening the duration with a hardcoded value benifits everyone; and > before Alexandre's reply on old server/slow disks, I don't recall any report, > because the coroutines would already yield often enough, when waiting for IO > to > complete. So I am not sure whether they're broken in practice. > > Fam
