Re: [systemd-devel] journal: How to limit the file size of runtime system.journal
On 12/16/2013 02:30 PM, Zbigniew Jędrzejewski-Szmek wrote: On Mon, Dec 16, 2013 at 08:31:46AM +0100, Holger Winkelmann [TP] wrote: Hi, Is there any particular reason? I think thresold for runtime journal size can lower much because in initramfs it's not supposed to have much logs. First, there are some data strcutures which are allocated when the file is created, and if the file was very small, relatively more space would wasted. Second, repeated fields are not stored, just referenced, so things become more efficient when the file is not too small. But neither is fundamental reason, and with some tweaking the journal could be made to work much smaller files. I understand. These are really good points when logs are relatively large, ie. the journal is stored on a real disk. However when it's in initramfs context, journal is stored in tmpfs which is using the real memory resource as it's backend. 4 MB seems a little bit overkill especially when memory is quite limited case, like kdump. To be more specific, I think 512 KB or 1 MB is a fairly large enough nubmer when journal is stored to a volatile backend. We totally agree that a minimum size must be below 1MB either on flash or ramfs for embedded devices. otherwise you end up with two solutions for smaller and bigger devices. Is there any reference about the overhead if you use smaller file size? Is there technical limitation for a minimum size? No, there's no real technical limitation. Except some hero should go through src/jounal/journal-file.c and adjust all the constants that they also work with very small files. Zbyszek Hi, the minimum file size changed in version 203 from 64KiB to 4MiB. Is there a special reason for this? The relevant code line seems to be #define JOURNAL_FILE_SIZE_MIN (4ULL*1024ULL*1024ULL) /* 4 MiB */ which did not change in 208. Sascha ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] journal: How to limit the file size of runtime system.journal
On Mon, Dec 16, 2013 at 08:31:46AM +0100, Holger Winkelmann [TP] wrote: Hi, Is there any particular reason? I think thresold for runtime journal size can lower much because in initramfs it's not supposed to have much logs. First, there are some data strcutures which are allocated when the file is created, and if the file was very small, relatively more space would wasted. Second, repeated fields are not stored, just referenced, so things become more efficient when the file is not too small. But neither is fundamental reason, and with some tweaking the journal could be made to work much smaller files. I understand. These are really good points when logs are relatively large, ie. the journal is stored on a real disk. However when it's in initramfs context, journal is stored in tmpfs which is using the real memory resource as it's backend. 4 MB seems a little bit overkill especially when memory is quite limited case, like kdump. To be more specific, I think 512 KB or 1 MB is a fairly large enough nubmer when journal is stored to a volatile backend. We totally agree that a minimum size must be below 1MB either on flash or ramfs for embedded devices. otherwise you end up with two solutions for smaller and bigger devices. Is there any reference about the overhead if you use smaller file size? Is there technical limitation for a minimum size? No, there's no real technical limitation. Except some hero should go through src/jounal/journal-file.c and adjust all the constants that they also work with very small files. Zbyszek ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] journal: How to limit the file size of runtime system.journal
On 12/13/13 at 02:18pm, Zbigniew Jędrzejewski-Szmek wrote: On Fri, Dec 13, 2013 at 01:49:51PM +0800, WANG Chao wrote: On 12/13/13 at 06:42am, Zbigniew Jędrzejewski-Szmek wrote: On Fri, Dec 13, 2013 at 01:33:17PM +0800, WANG Chao wrote: Hi, In kdump environment, memory resource is quite limited. I find that the runtime journal file (/run/log/journal/$id/system.journal) is 4 MB and I think that is too much for a initramfs context. After tuning both RuntimeMaxUse=1% or RuntimeMaxFileSiz=100K, I find system.journal is still 4 MB in size. So here comes my questions: 1. Did miss use of these two config options? Because regarding the journald.conf(5), it seems I was totally doing it right. 4MB is the minimum. Those settings are ignored if you set anything lower. Is there any particular reason? I think thresold for runtime journal size can lower much because in initramfs it's not supposed to have much logs. First, there are some data strcutures which are allocated when the file is created, and if the file was very small, relatively more space would wasted. Second, repeated fields are not stored, just referenced, so things become more efficient when the file is not too small. But neither is fundamental reason, and with some tweaking the journal could be made to work much smaller files. I understand. These are really good points when logs are relatively large, ie. the journal is stored on a real disk. However when it's in initramfs context, journal is stored in tmpfs which is using the real memory resource as it's backend. 4 MB seems a little bit overkill especially when memory is quite limited case, like kdump. To be more specific, I think 512 KB or 1 MB is a fairly large enough nubmer when journal is stored to a volatile backend. Thanks WANG Chao ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] journal: How to limit the file size of runtime system.journal
Hi, Is there any particular reason? I think thresold for runtime journal size can lower much because in initramfs it's not supposed to have much logs. First, there are some data strcutures which are allocated when the file is created, and if the file was very small, relatively more space would wasted. Second, repeated fields are not stored, just referenced, so things become more efficient when the file is not too small. But neither is fundamental reason, and with some tweaking the journal could be made to work much smaller files. I understand. These are really good points when logs are relatively large, ie. the journal is stored on a real disk. However when it's in initramfs context, journal is stored in tmpfs which is using the real memory resource as it's backend. 4 MB seems a little bit overkill especially when memory is quite limited case, like kdump. To be more specific, I think 512 KB or 1 MB is a fairly large enough nubmer when journal is stored to a volatile backend. We totally agree that a minimum size must be below 1MB either on flash or ramfs for embedded devices. otherwise you end up with two solutions for smaller and bigger devices. Is there any reference about the overhead if you use smaller file size? Is there technical limitation for a minimum size? Thanks, Holger Thanks WANG Chao ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel -- Holger Winkelmann ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] journal: How to limit the file size of runtime system.journal
On Fri, Dec 13, 2013 at 01:49:51PM +0800, WANG Chao wrote: On 12/13/13 at 06:42am, Zbigniew Jędrzejewski-Szmek wrote: On Fri, Dec 13, 2013 at 01:33:17PM +0800, WANG Chao wrote: Hi, In kdump environment, memory resource is quite limited. I find that the runtime journal file (/run/log/journal/$id/system.journal) is 4 MB and I think that is too much for a initramfs context. After tuning both RuntimeMaxUse=1% or RuntimeMaxFileSiz=100K, I find system.journal is still 4 MB in size. So here comes my questions: 1. Did miss use of these two config options? Because regarding the journald.conf(5), it seems I was totally doing it right. 4MB is the minimum. Those settings are ignored if you set anything lower. Is there any particular reason? I think thresold for runtime journal size can lower much because in initramfs it's not supposed to have much logs. First, there are some data strcutures which are allocated when the file is created, and if the file was very small, relatively more space would wasted. Second, repeated fields are not stored, just referenced, so things become more efficient when the file is not too small. But neither is fundamental reason, and with some tweaking the journal could be made to work much smaller files. Zbyszek ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
[systemd-devel] journal: How to limit the file size of runtime system.journal
Hi, In kdump environment, memory resource is quite limited. I find that the runtime journal file (/run/log/journal/$id/system.journal) is 4 MB and I think that is too much for a initramfs context. After tuning both RuntimeMaxUse=1% or RuntimeMaxFileSiz=100K, I find system.journal is still 4 MB in size. So here comes my questions: 1. Did miss use of these two config options? Because regarding the journald.conf(5), it seems I was totally doing it right. 2. If I was doing it wrong, how can I limit this file size? -- Thanks WANG Chao ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] journal: How to limit the file size of runtime system.journal
On Fri, Dec 13, 2013 at 01:33:17PM +0800, WANG Chao wrote: Hi, In kdump environment, memory resource is quite limited. I find that the runtime journal file (/run/log/journal/$id/system.journal) is 4 MB and I think that is too much for a initramfs context. After tuning both RuntimeMaxUse=1% or RuntimeMaxFileSiz=100K, I find system.journal is still 4 MB in size. So here comes my questions: 1. Did miss use of these two config options? Because regarding the journald.conf(5), it seems I was totally doing it right. 4MB is the minimum. Those settings are ignored if you set anything lower. 2. If I was doing it wrong, how can I limit this file size? It's not possible below this threshold. Zbyszek ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
