Hi Reinette,
On 7/21/25 22:32, Reinette Chatre wrote:
> Hi Babu,
>
> On 7/10/25 10:16 AM, Babu Moger wrote:
>> "io_alloc" feature enables direct insertion of data from I/O devices into
>> the cache. By directly caching data from I/O devices rather than first
>> storing the I/O data in DRAM, it reduces the demands on DRAM bandwidth and
>> reduces latency to the processor consuming the I/O data.
>>
>> Provide the interface to modify io_alloc CBMs (Capacity Bit Mask) when
>
> "Provide the interface to modify io_alloc CBMs (Capacity Bit Mask) when feature is
> enabled." ->
> "Enable users to modify io_alloc CBMs (Capacity Bit Masks) via the io_alloc_cbm
> resctrl file when io_alloc is enabled."?
Sure.
>
>> feature is enabled. Update the CBMs for both CDP_DATA and CDP_CODE when CDP
>> is enabled.
>>
>> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
>> ---
>
> ...
>
>> ---
>> Documentation/filesystems/resctrl.rst | 8 ++
>> fs/resctrl/ctrlmondata.c | 4 +-
>> fs/resctrl/internal.h | 2 +
>> fs/resctrl/rdtgroup.c | 112 +++++++++++++++++++++++++-
>> 4 files changed, 123 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
>> index c22a9dd667cd..b9c3ffdec27f 100644
>> --- a/Documentation/filesystems/resctrl.rst
>> +++ b/Documentation/filesystems/resctrl.rst
>> @@ -189,6 +189,14 @@ related to allocation:
>> # cat /sys/fs/resctrl/info/L3/io_alloc_cbm
>> 0=ffff;1=ffff
>>
>> + CBMs can be configured by writing to the interface.
>> +
>> + Example::
>> +
>> + # echo 1=FF > /sys/fs/resctrl/info/L3/io_alloc_cbm
>> + # cat /sys/fs/resctrl/info/L3/io_alloc_cbm
>> + 0=ffff;1=00ff
>> +
>> When CDP is enabled "io_alloc_cbm" associated with the DATA and CODE
>> resources may reflect the same values. For example, values read from and
>> written to /sys/fs/resctrl/info/L3DATA/io_alloc_cbm may be reflected by
>> diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
>> index 5c16557fb7a8..23c72a5ac043 100644
>> --- a/fs/resctrl/ctrlmondata.c
>> +++ b/fs/resctrl/ctrlmondata.c
>> @@ -148,8 +148,8 @@ static bool cbm_validate(char *buf, u32 *data, struct rdt_resource *r)
>> * Read one cache bit mask (hex). Check that it is valid for the current
>> * resource type.
>> */
>> -static int parse_cbm(struct rdt_parse_data *data, struct resctrl_schema *s,
>> - struct rdt_ctrl_domain *d)
>> +int parse_cbm(struct rdt_parse_data *data, struct resctrl_schema *s,
>> + struct rdt_ctrl_domain *d)
>
> This can remain static by moving caller to ctrlmondata.c
Yes.
>
>> {
>> enum rdtgrp_mode mode = data->mode;
>> struct resctrl_staged_config *cfg;
>> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
>> index ab76a1e2e679..011564e69ed5 100644
>> --- a/fs/resctrl/internal.h
>> +++ b/fs/resctrl/internal.h
>> @@ -382,6 +382,8 @@ bool closid_allocated(unsigned int closid);
>> int resctrl_find_cleanest_closid(void);
>> void show_doms(struct seq_file *s, struct resctrl_schema *schema,
>> char *name, int closid);
>> +int parse_cbm(struct rdt_parse_data *data, struct resctrl_schema *s,
>> + struct rdt_ctrl_domain *d);
>>
>> #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
>> int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index 008657e43656..1093ec5e385b 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -2036,6 +2036,115 @@ static int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of,
>> return ret;
>> }
>>
>> +static int resctrl_io_alloc_parse_line(char *line, struct rdt_resource *r,
>> + struct resctrl_schema *s, u32 closid)
>
> Please move to ctrlmondata.c
Yes.
>
>> +{
>> + struct rdt_parse_data data;
>> + struct rdt_ctrl_domain *d;
>> + char *dom = NULL, *id;
>> + unsigned long dom_id;
>> +
>> +next:
>> + if (!line || line[0] == '\0')
>> + return 0;
>> +
>> + dom = strsep(&line, ";");
>> + id = strsep(&dom, "=");
>> + if (!dom || kstrtoul(id, 10, &dom_id)) {
>> + rdt_last_cmd_puts("Missing '=' or non-numeric domain\n");
>> + return -EINVAL;
>> + }
>> +
>> + dom = strim(dom);
>> + list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
>> + if (d->hdr.id == dom_id) {
>> + data.buf = dom;
>> + data.mode = RDT_MODE_SHAREABLE;
>> + data.closid = closid;
>> + if (parse_cbm(&data, s, d))
>> + return -EINVAL;
>> + goto next;
>> + }
>> + }
>> + return -EINVAL;
>> +}
>> +
>> +static ssize_t resctrl_io_alloc_cbm_write(struct kernfs_open_file *of,
>> + char *buf, size_t nbytes, loff_t off)
>
> Please move to ctrlmondata.c
Yes.
>
>> +{
>> + struct resctrl_schema *s = rdt_kn_parent_priv(of->kn);
>> + enum resctrl_conf_type peer_type;
>> + struct rdt_resource *r = s->res;
>> + struct resctrl_schema *peer_s;
>> + u32 io_alloc_closid;
>> + char *peer_buf;
>> + int ret = 0;
>> +
>> + /* Valid input requires a trailing newline */
>> + if (nbytes == 0 || buf[nbytes - 1] != '\n')
>> + return -EINVAL;
>> +
>> + buf[nbytes - 1] = '\0';
>> +
>> + cpus_read_lock();
>> + mutex_lock(&rdtgroup_mutex);
>> +
>> + if (!r->cache.io_alloc_capable) {
>> + rdt_last_cmd_printf("io_alloc is not supported on %s\n", s->name);
>
> rdt_last_cmd_clear() is required before any write to the buffer.
Added now.
>
>> + ret = -EINVAL;
>> + goto out_unlock;
>> + }
>> +
>> + rdt_last_cmd_clear();
>> + rdt_staged_configs_clear();
>> +
>> + if (!resctrl_arch_get_io_alloc_enabled(r)) {
>> + rdt_last_cmd_printf("io_alloc is not enabled on %s\n", s->name);
>> + ret = -EINVAL;
>
> Inconsistent error codes when io_alloc is not enabled. resctrl_io_alloc_write()
> and resctrl_io_alloc_cbm_show() returns -ENODEV.
Changed it to -ENODEV.
>
>> + goto out_unlock;
>> + }
>> +
>> + io_alloc_closid = resctrl_io_alloc_closid(r);
>> +
>> + /*
>> + * When CDP is enabled, update the schema for both CDP_DATA and CDP_CODE.
>> + * Since the buffer is altered during parsing, create a copy to handle
>> + * peer schemata separately.
>> + */
>> + if (resctrl_arch_get_cdp_enabled(r->rid)) {
>> + peer_type = resctrl_peer_type(s->conf_type);
>> + peer_s = resctrl_get_schema(peer_type);
>> + peer_buf = kmalloc(nbytes, GFP_KERNEL);
>> + if (!peer_buf) {
>> + rdt_last_cmd_puts("Out of Memory - io_alloc update failed\n");
>> + ret = -ENOMEM;
>> + goto out_unlock;
>> + }
>> +
>> + memcpy(peer_buf, buf, nbytes);
>> +
>> + if (peer_s)
>> + ret = resctrl_io_alloc_parse_line(peer_buf, r, peer_s, io_alloc_closid);
>
> Similar to resctrl_io_alloc_write() this looks unnecessary. I think this can be simplified
> by moving the CDP check to resctrl_io_alloc_parse_line() where the provided CBM can be parsed
> *once* and the staged config of a CDP type just copied to the staged config of its peer type.
Yes. Changed it now.
>
>> +
>> + kfree(peer_buf);
>> + }
>> +
>> + if (!ret)
>> + ret = resctrl_io_alloc_parse_line(buf, r, s, io_alloc_closid);
>> +
>> + if (ret)
>> + goto out_unlock;
>> +
>> + ret = resctrl_arch_update_domains(r, io_alloc_closid);
>> +
>> +out_unlock:
>> + rdt_staged_configs_clear();
>> + mutex_unlock(&rdtgroup_mutex);
>> + cpus_read_unlock();
>> +
>> + return ret ?: nbytes;
>> +}
>> +
>> /* rdtgroup information files for one cache resource. */
>> static struct rftype res_common_files[] = {
>> {
>> @@ -2135,9 +2244,10 @@ static struct rftype res_common_files[] = {
>> },
>> {
>> .name = "io_alloc_cbm",
>> - .mode = 0444,
>> + .mode = 0644,
>> .kf_ops = &rdtgroup_kf_single_ops,
>> .seq_show = resctrl_io_alloc_cbm_show,
>> + .write = resctrl_io_alloc_cbm_write,
>> },
>> {
>> .name = "max_threshold_occupancy",
>
> Reinette
>
--
Thanks
Babu Moger
